diff --git a/b2g/components/test/mochitest/screenshot_helper.js b/b2g/components/test/mochitest/screenshot_helper.js
index d10234f9281..cf40528f0ee 100644
--- a/b2g/components/test/mochitest/screenshot_helper.js
+++ b/b2g/components/test/mochitest/screenshot_helper.js
@@ -1,6 +1,8 @@
 const Cu = Components.utils;
 const Ci = Components.interfaces;
 
+Cu.importGlobalProperties(['File']);
+
 const { Services } = Cu.import("resource://gre/modules/Services.jsm");
 
 // Load a duplicated copy of the jsm to prevent messing with the currently running one
@@ -25,7 +27,7 @@ function next() {
 let steps = [
   function getScreenshot() {
     let screenshot = Screenshot.get();
-    assert.ok(screenshot instanceof Ci.nsIDOMFile,
+    assert.ok(screenshot instanceof File,
               "Screenshot.get() returns a File");
     next();
   },
diff --git a/dom/apps/ImportExport.jsm b/dom/apps/ImportExport.jsm
index e990b9a6c53..a2b13f61927 100644
--- a/dom/apps/ImportExport.jsm
+++ b/dom/apps/ImportExport.jsm
@@ -14,6 +14,8 @@ Cu.import("resource://gre/modules/AppsUtils.jsm");
 Cu.import("resource://gre/modules/Promise.jsm");
 Cu.import("resource://gre/modules/Webapps.jsm");
 
+Cu.importGlobalProperties(['File']);
+
 XPCOMUtils.defineLazyModuleGetter(this, "FileUtils",
   "resource://gre/modules/FileUtils.jsm");
 
@@ -284,7 +286,7 @@ this.ImportExport = {
       throw "NoBlobFound";
     }
 
-    let isFileBlob = aBlob instanceof Ci.nsIDOMFile;
+    let isFileBlob = aBlob instanceof File;
     // We can't QI the DOMFile to nsIFile, so we need to create one.
     let zipFile = Cc["@mozilla.org/file/local;1"].createInstance(Ci.nsIFile);
     if (!isFileBlob) {
@@ -498,7 +500,7 @@ this.ImportExport = {
       throw "NoBlobFound";
     }
 
-    let isFileBlob = aBlob instanceof Ci.nsIDOMFile;
+    let isFileBlob = aBlob instanceof File;
     // We can't QI the DOMFile to nsIFile, so we need to create one.
     let zipFile = Cc["@mozilla.org/file/local;1"].createInstance(Ci.nsIFile);
     if (!isFileBlob) {
diff --git a/dom/base/File.cpp b/dom/base/File.cpp
index 2cb3bde2212..c8e9d94cd95 100644
--- a/dom/base/File.cpp
+++ b/dom/base/File.cpp
@@ -439,22 +439,6 @@ Blob::GetInternalStream(nsIInputStream** aStream)
 ////////////////////////////////////////////////////////////////////////////
 // mozilla::dom::File implementation
 
-NS_IMPL_CYCLE_COLLECTION_CLASS(File)
-
-NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(File, Blob)
-NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
-
-NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(File, Blob)
-NS_IMPL_CYCLE_COLLECTION_UNLINK_END
-
-NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(File)
-  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIDOMFile)
-  NS_INTERFACE_MAP_ENTRY(nsIDOMFile)
-NS_INTERFACE_MAP_END_INHERITING(Blob)
-
-NS_IMPL_ADDREF_INHERITED(File, Blob)
-NS_IMPL_RELEASE_INHERITED(File, Blob)
-
 File::File(nsISupports* aParent, BlobImpl* aImpl)
   : Blob(aParent, aImpl)
 {
@@ -1282,9 +1266,9 @@ FileList::GetLength(uint32_t* aLength)
 }
 
 NS_IMETHODIMP
-FileList::Item(uint32_t aIndex, nsIDOMFile **aFile)
+FileList::Item(uint32_t aIndex, nsISupports** aFile)
 {
-  nsRefPtr<File> file = Item(aIndex);
+  nsCOMPtr<nsIDOMBlob> file = Item(aIndex);
   file.forget(aFile);
   return NS_OK;
 }
diff --git a/dom/base/File.h b/dom/base/File.h
index a7ecd7fa145..5c660b11a40 100644
--- a/dom/base/File.h
+++ b/dom/base/File.h
@@ -20,7 +20,7 @@
 #include "nsAutoPtr.h"
 #include "nsCycleCollectionParticipant.h"
 #include "nsCOMPtr.h"
-#include "nsIDOMFile.h"
+#include "nsIDOMBlob.h"
 #include "nsIDOMFileList.h"
 #include "nsIFile.h"
 #include "nsIMutable.h"
@@ -157,17 +157,10 @@ private:
 };
 
 class File final : public Blob
-                 , public nsIDOMFile
 {
   friend class Blob;
 
 public:
-  NS_DECL_NSIDOMFILE
-  NS_FORWARD_NSIDOMBLOB(Blob::)
-
-  NS_DECL_ISUPPORTS_INHERITED
-  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(File, Blob);
-
   // Note: BlobImpl must be a File in order to use this method.
   // Check impl->IsFile().
   static File*
diff --git a/dom/base/FileIOObject.h b/dom/base/FileIOObject.h
index cb96b93b89c..67069d8971c 100644
--- a/dom/base/FileIOObject.h
+++ b/dom/base/FileIOObject.h
@@ -9,7 +9,6 @@
 
 #include "mozilla/DOMEventTargetHelper.h"
 #include "nsIFile.h"
-#include "nsIDOMFile.h"
 #include "nsITimer.h"
 #include "nsCOMPtr.h"
 #include "nsIAsyncInputStream.h"
diff --git a/dom/base/moz.build b/dom/base/moz.build
index 27fcf10ad55..acbaa665e83 100644
--- a/dom/base/moz.build
+++ b/dom/base/moz.build
@@ -11,10 +11,10 @@ XPIDL_SOURCES += [
     'nsIContentPolicy.idl',
     'nsIContentPolicyBase.idl',
     'nsIDocumentEncoder.idl',
+    'nsIDOMBlob.idl',
     'nsIDOMDataChannel.idl',
     'nsIDOMDOMCursor.idl',
     'nsIDOMDOMRequest.idl',
-    'nsIDOMFile.idl',
     'nsIDOMFileList.idl',
     'nsIDOMFileReader.idl',
     'nsIDOMFormData.idl',
diff --git a/dom/base/nsDOMWindowUtils.cpp b/dom/base/nsDOMWindowUtils.cpp
index 24eb63b19b7..2d026e72478 100644
--- a/dom/base/nsDOMWindowUtils.cpp
+++ b/dom/base/nsDOMWindowUtils.cpp
@@ -2593,7 +2593,7 @@ nsDOMWindowUtils::GetContainerElement(nsIDOMElement** aResult)
 
 NS_IMETHODIMP
 nsDOMWindowUtils::WrapDOMFile(nsIFile *aFile,
-                              nsIDOMFile **aDOMFile)
+                              nsISupports **aDOMFile)
 {
   MOZ_RELEASE_ASSERT(nsContentUtils::IsCallerChrome());
 
@@ -2609,8 +2609,8 @@ nsDOMWindowUtils::WrapDOMFile(nsIFile *aFile,
     return NS_ERROR_FAILURE;
   }
 
-  nsRefPtr<File> file = File::CreateFromFile(innerWindow, aFile);
-  file.forget(aDOMFile);
+  nsCOMPtr<nsIDOMBlob> blob = File::CreateFromFile(innerWindow, aFile);
+  blob.forget(aDOMFile);
   return NS_OK;
 }
 
diff --git a/dom/base/nsFrameLoader.cpp b/dom/base/nsFrameLoader.cpp
index d9b2a3cf049..114a9b176a7 100644
--- a/dom/base/nsFrameLoader.cpp
+++ b/dom/base/nsFrameLoader.cpp
@@ -23,7 +23,6 @@
 #include "nsIContentViewer.h"
 #include "nsIDocument.h"
 #include "nsIDOMDocument.h"
-#include "nsIDOMFile.h"
 #include "nsPIDOMWindow.h"
 #include "nsIWebNavigation.h"
 #include "nsIWebProgress.h"
diff --git a/dom/base/nsIDOMFile.idl b/dom/base/nsIDOMBlob.idl
similarity index 80%
rename from dom/base/nsIDOMFile.idl
rename to dom/base/nsIDOMBlob.idl
index f0f643a33be..efdc1be84f3 100644
--- a/dom/base/nsIDOMFile.idl
+++ b/dom/base/nsIDOMBlob.idl
@@ -53,14 +53,3 @@ interface nsIDOMBlob : nsISupports
   // Return true if this blob is a memory file.
   [notxpcom] bool isMemoryFile();
 };
-
-// We want to avoid multiple inheritance of nsIDOMBlob so we can downcast from
-// nsIDOMBlob to Blob safely.  Our chain is:
-//  - Blob -> nsIDOMBlob
-//  - File -> nsIDOMFile and Blob
-[scriptable, builtinclass, uuid(26e292a6-f5aa-4560-b523-ae22a4c7dfca)]
-interface nsIDOMFile : nsISupports
-{
-  // Empty interface used by addons and some test to check if the object is a
-  // blob or file. This interface will be removed by bug 1163388
-};
diff --git a/dom/base/nsIDOMFileList.idl b/dom/base/nsIDOMFileList.idl
index 29186604c5f..338bd72793e 100644
--- a/dom/base/nsIDOMFileList.idl
+++ b/dom/base/nsIDOMFileList.idl
@@ -5,11 +5,10 @@
 
 #include "nsISupports.idl"
 
-interface nsIDOMFile;
-
-[uuid(283aa7b2-da81-4c72-aea2-9797b440fe34)]
+[uuid(57128a85-34de-42db-a252-84dd57724a59)]
 interface nsIDOMFileList : nsISupports
 {
   readonly attribute unsigned long length;
-  nsIDOMFile item(in unsigned long index);
+  // returns a DOM File object
+  nsISupports item(in unsigned long index);
 };
diff --git a/dom/bindings/ToJSValue.h b/dom/bindings/ToJSValue.h
index 5cfef1895ce..f80652e2c58 100644
--- a/dom/bindings/ToJSValue.h
+++ b/dom/bindings/ToJSValue.h
@@ -172,7 +172,7 @@ ToJSValue(JSContext* aCx,
 }
 
 // Accept objects that inherit from nsISupports but not nsWrapperCache (e.g.
-// nsIDOMFile).
+// DOM File).
 template <class T>
 MOZ_WARN_UNUSED_RESULT
 typename EnableIf<!IsBaseOf<nsWrapperCache, T>::value &&
diff --git a/dom/bluetooth/bluedroid/BluetoothOppManager.cpp b/dom/bluetooth/bluedroid/BluetoothOppManager.cpp
index 1d20800417e..ac325f088e9 100644
--- a/dom/bluetooth/bluedroid/BluetoothOppManager.cpp
+++ b/dom/bluetooth/bluedroid/BluetoothOppManager.cpp
@@ -72,14 +72,14 @@ BEGIN_BLUETOOTH_NAMESPACE
 class BluetoothOppManager::SendFileBatch final
 {
 public:
-  SendFileBatch(const nsAString& aDeviceAddress, nsIDOMBlob* aBlob)
+  SendFileBatch(const nsAString& aDeviceAddress, Blob* aBlob)
     : mDeviceAddress(aDeviceAddress)
   {
     mBlobs.AppendElement(aBlob);
   }
 
   nsString mDeviceAddress;
-  nsCOMArray<nsIDOMBlob> mBlobs;
+  nsTArray<nsRefPtr<Blob>> mBlobs;
 };
 
 NS_IMETHODIMP
@@ -420,7 +420,7 @@ BluetoothOppManager::SendFile(const nsAString& aDeviceAddress,
 
 bool
 BluetoothOppManager::SendFile(const nsAString& aDeviceAddress,
-                              nsIDOMBlob* aBlob)
+                              Blob* aBlob)
 {
   MOZ_ASSERT(NS_IsMainThread());
 
@@ -434,7 +434,7 @@ BluetoothOppManager::SendFile(const nsAString& aDeviceAddress,
 
 void
 BluetoothOppManager::AppendBlobToSend(const nsAString& aDeviceAddress,
-                                      nsIDOMBlob* aBlob)
+                                      Blob* aBlob)
 {
   MOZ_ASSERT(NS_IsMainThread());
 
@@ -794,7 +794,7 @@ BluetoothOppManager::RetrieveSentFileName()
 {
   mFileName.Truncate();
 
-  nsRefPtr<File> file = static_cast<Blob*>(mBlob.get()).ToFile();
+  nsRefPtr<File> file = static_cast<Blob*>(mBlob.get())->ToFile();
   if (file) {
     file->GetName(mFileName);
   }
diff --git a/dom/bluetooth/bluedroid/BluetoothOppManager.h b/dom/bluetooth/bluedroid/BluetoothOppManager.h
index d87bb0aef08..5833846e4a7 100644
--- a/dom/bluetooth/bluedroid/BluetoothOppManager.h
+++ b/dom/bluetooth/bluedroid/BluetoothOppManager.h
@@ -14,13 +14,13 @@
 #include "mozilla/ipc/SocketBase.h"
 #include "nsCOMArray.h"
 
-class nsIDOMBlob;
 class nsIOutputStream;
 class nsIInputStream;
 class nsIVolumeMountLock;
 
 namespace mozilla {
 namespace dom {
+class Blob;
 class BlobParent;
 }
 }
@@ -55,7 +55,7 @@ public:
   bool Listen();
 
   bool SendFile(const nsAString& aDeviceAddress, BlobParent* aActor);
-  bool SendFile(const nsAString& aDeviceAddress, nsIDOMBlob* aBlob);
+  bool SendFile(const nsAString& aDeviceAddress, Blob* aBlob);
   bool StopSendingFile();
   bool ConfirmReceivingFile(bool aConfirm);
 
@@ -102,7 +102,7 @@ private:
   void NotifyAboutFileChange();
   bool AcquireSdcardMountLock();
   void SendObexData(uint8_t* aData, uint8_t aOpcode, int aSize);
-  void AppendBlobToSend(const nsAString& aDeviceAddress, nsIDOMBlob* aBlob);
+  void AppendBlobToSend(const nsAString& aDeviceAddress, Blob* aBlob);
   void DiscardBlobsToSend();
   bool ProcessNextBatch();
   void ConnectInternal(const nsAString& aDeviceAddress);
@@ -199,7 +199,7 @@ private:
   nsAutoArrayPtr<uint8_t> mReceivedDataBuffer;
 
   int mCurrentBlobIndex;
-  nsCOMPtr<nsIDOMBlob> mBlob;
+  nsRefPtr<Blob> mBlob;
   nsTArray<SendFileBatch> mBatches;
 
   /**
diff --git a/dom/bluetooth/bluedroid/BluetoothServiceBluedroid.cpp b/dom/bluetooth/bluedroid/BluetoothServiceBluedroid.cpp
index cf7b6118d43..c3f2eb41e3c 100644
--- a/dom/bluetooth/bluedroid/BluetoothServiceBluedroid.cpp
+++ b/dom/bluetooth/bluedroid/BluetoothServiceBluedroid.cpp
@@ -1827,7 +1827,7 @@ BluetoothServiceBluedroid::SendFile(const nsAString& aDeviceAddress,
 
 void
 BluetoothServiceBluedroid::SendFile(const nsAString& aDeviceAddress,
-                                    nsIDOMBlob* aBlob,
+                                    Blob* aBlob,
                                     BluetoothReplyRunnable* aRunnable)
 {
   MOZ_ASSERT(NS_IsMainThread());
diff --git a/dom/bluetooth/bluedroid/BluetoothServiceBluedroid.h b/dom/bluetooth/bluedroid/BluetoothServiceBluedroid.h
index 57fe121aba7..bbebf2c96c7 100644
--- a/dom/bluetooth/bluedroid/BluetoothServiceBluedroid.h
+++ b/dom/bluetooth/bluedroid/BluetoothServiceBluedroid.h
@@ -130,7 +130,7 @@ public:
 
   virtual void
   SendFile(const nsAString& aDeviceAddress,
-           nsIDOMBlob* aBlob,
+           Blob* aBlob,
            BluetoothReplyRunnable* aRunnable);
 
   virtual void
@@ -435,7 +435,7 @@ public:
 
   virtual void
   SendFile(const nsAString& aDeviceAddress,
-           nsIDOMBlob* aBlob,
+           Blob* aBlob,
            BluetoothReplyRunnable* aRunnable);
 
   virtual void
diff --git a/dom/bluetooth/bluetooth2/BluetoothService.h b/dom/bluetooth/bluetooth2/BluetoothService.h
index 99fcfab7513..d362a79cc35 100644
--- a/dom/bluetooth/bluetooth2/BluetoothService.h
+++ b/dom/bluetooth/bluetooth2/BluetoothService.h
@@ -12,15 +12,13 @@
 #include "BluetoothProfileManagerBase.h"
 #include "nsAutoPtr.h"
 #include "nsClassHashtable.h"
-#include "nsIDOMFile.h"
 #include "nsIObserver.h"
 #include "nsTObserverArray.h"
 #include "nsThreadUtils.h"
 
-class nsIDOMBlob;
-
 namespace mozilla {
 namespace dom {
+class Blob;
 class BlobChild;
 class BlobParent;
 }
@@ -295,7 +293,7 @@ public:
 
   virtual void
   SendFile(const nsAString& aDeviceAddress,
-           nsIDOMBlob* aBlob,
+           Blob* aBlob,
            BluetoothReplyRunnable* aRunnable) = 0;
 
   virtual void
diff --git a/dom/bluetooth/bluetooth2/ipc/BluetoothServiceChildProcess.cpp b/dom/bluetooth/bluetooth2/ipc/BluetoothServiceChildProcess.cpp
index 867df1aeada..303769395c9 100644
--- a/dom/bluetooth/bluetooth2/ipc/BluetoothServiceChildProcess.cpp
+++ b/dom/bluetooth/bluetooth2/ipc/BluetoothServiceChildProcess.cpp
@@ -316,7 +316,7 @@ BluetoothServiceChildProcess::SendFile(
 void
 BluetoothServiceChildProcess::SendFile(
   const nsAString& aDeviceAddress,
-  nsIDOMBlob* aBlobChild,
+  Blob* aBlobChild,
   BluetoothReplyRunnable* aRunnable)
 {
   // Parent-process-only method
diff --git a/dom/bluetooth/bluetooth2/ipc/BluetoothServiceChildProcess.h b/dom/bluetooth/bluetooth2/ipc/BluetoothServiceChildProcess.h
index ab7bdbac5a7..aebf930de77 100644
--- a/dom/bluetooth/bluetooth2/ipc/BluetoothServiceChildProcess.h
+++ b/dom/bluetooth/bluetooth2/ipc/BluetoothServiceChildProcess.h
@@ -140,7 +140,7 @@ public:
 
   virtual void
   SendFile(const nsAString& aDeviceAddress,
-           nsIDOMBlob* aBlob,
+           Blob* aBlob,
            BluetoothReplyRunnable* aRunnable) override;
 
   virtual void
diff --git a/dom/fetch/InternalResponse.cpp b/dom/fetch/InternalResponse.cpp
index 6d7c1125b4d..6ee065c7bc3 100644
--- a/dom/fetch/InternalResponse.cpp
+++ b/dom/fetch/InternalResponse.cpp
@@ -6,8 +6,6 @@
 
 #include "InternalResponse.h"
 
-#include "nsIDOMFile.h"
-
 #include "mozilla/dom/InternalHeaders.h"
 #include "nsStreamUtils.h"
 #include "nsSerializationHelper.h"
diff --git a/dom/html/HTMLCanvasElement.cpp b/dom/html/HTMLCanvasElement.cpp
index 85992ced064..e3fbbb61962 100644
--- a/dom/html/HTMLCanvasElement.cpp
+++ b/dom/html/HTMLCanvasElement.cpp
@@ -647,16 +647,22 @@ HTMLCanvasElement::MozGetAsFile(const nsAString& aName,
                                 const nsAString& aType,
                                 ErrorResult& aRv)
 {
-  nsCOMPtr<nsIDOMFile> file;
+  nsCOMPtr<nsISupports> file;
   aRv = MozGetAsFile(aName, aType, getter_AddRefs(file));
-  nsRefPtr<File> tmp = static_cast<File*>(file.get());
-  return tmp.forget();
+  if (NS_WARN_IF(aRv.Failed())) {
+    return nullptr;
+  }
+
+  nsCOMPtr<nsIDOMBlob> blob = do_QueryInterface(file);
+  nsRefPtr<Blob> domBlob = static_cast<Blob*>(blob.get());
+  MOZ_ASSERT(domBlob->IsFile());
+  return domBlob->ToFile();
 }
 
 NS_IMETHODIMP
 HTMLCanvasElement::MozGetAsFile(const nsAString& aName,
                                 const nsAString& aType,
-                                nsIDOMFile** aResult)
+                                nsISupports** aResult)
 {
   OwnerDoc()->WarnOnceAbout(nsIDocument::eMozGetAsFile);
 
@@ -672,7 +678,7 @@ HTMLCanvasElement::MozGetAsFile(const nsAString& aName,
 nsresult
 HTMLCanvasElement::MozGetAsBlobImpl(const nsAString& aName,
                                     const nsAString& aType,
-                                    nsIDOMFile** aResult)
+                                    nsISupports** aResult)
 {
   nsCOMPtr<nsIInputStream> stream;
   nsAutoString type(aType);
@@ -696,7 +702,7 @@ HTMLCanvasElement::MozGetAsBlobImpl(const nsAString& aName,
   nsCOMPtr<nsPIDOMWindow> win = do_QueryInterface(OwnerDoc()->GetScopeObject());
 
   // The File takes ownership of the buffer
-  nsRefPtr<File> file =
+  nsCOMPtr<nsIDOMBlob> file =
     File::CreateMemoryFile(win, imgData, (uint32_t)imgSize, aName, type,
                            PR_Now());
 
diff --git a/dom/html/HTMLCanvasElement.h b/dom/html/HTMLCanvasElement.h
index 5da35892100..fa28265f155 100644
--- a/dom/html/HTMLCanvasElement.h
+++ b/dom/html/HTMLCanvasElement.h
@@ -237,7 +237,7 @@ protected:
                          nsAString& aDataURL);
   nsresult MozGetAsBlobImpl(const nsAString& aName,
                             const nsAString& aType,
-                            nsIDOMFile** aResult);
+                            nsISupports** aResult);
   void CallPrintCallback();
 
   CanvasContextType mCurrentContextType;
diff --git a/dom/html/HTMLInputElement.cpp b/dom/html/HTMLInputElement.cpp
index a4404dd0f15..e7f2c876681 100644
--- a/dom/html/HTMLInputElement.cpp
+++ b/dom/html/HTMLInputElement.cpp
@@ -405,7 +405,9 @@ public:
       MOZ_ASSERT(blobImpl);
       blobImpl->SetPath(Substring(path, 0, uint32_t(length)));
     }
-    *aResult = domFile.forget().downcast<nsIDOMFile>().take();
+
+    nsCOMPtr<nsIDOMBlob> blob = domFile.get();
+    blob.forget(aResult);
     LookupAndCacheNext();
     return NS_OK;
   }
@@ -488,7 +490,7 @@ NS_IMPL_ISUPPORTS(DirPickerRecursiveFileEnumerator, nsISimpleEnumerator)
 
 /**
  * This may return nullptr if aDomFile's implementation of
- * nsIDOMFile::mozFullPathInternal does not successfully return a non-empty
+ * File::mozFullPathInternal does not successfully return a non-empty
  * string that is a valid path. This can happen on Firefox OS, for example,
  * where the file picker can create Blobs.
  */
@@ -537,9 +539,9 @@ public:
       nsCOMPtr<nsISupports> tmp;
       while (NS_SUCCEEDED(iter->HasMoreElements(&hasMore)) && hasMore) {
         iter->GetNext(getter_AddRefs(tmp));
-        nsCOMPtr<nsIDOMFile> domFile = do_QueryInterface(tmp);
-        MOZ_ASSERT(domFile);
-        mFileList.AppendElement(static_cast<File*>(domFile.get()));
+        nsCOMPtr<nsIDOMBlob> domBlob = do_QueryInterface(tmp);
+        MOZ_ASSERT(domBlob);
+        mFileList.AppendElement(static_cast<File*>(domBlob.get()));
         mFileListLength = mFileList.Length();
         if (mCanceled) {
           MOZ_ASSERT(!mInput, "This is bad - how did this happen?");
@@ -696,20 +698,23 @@ HTMLInputElement::nsFilePickerShownCallback::Done(int16_t aResult)
 
     while (NS_SUCCEEDED(iter->HasMoreElements(&hasMore)) && hasMore) {
       iter->GetNext(getter_AddRefs(tmp));
-      nsCOMPtr<nsIDOMFile> domFile = do_QueryInterface(tmp);
-      NS_WARN_IF_FALSE(domFile,
+      nsCOMPtr<nsIDOMBlob> domBlob = do_QueryInterface(tmp);
+      NS_WARN_IF_FALSE(domBlob,
                        "Null file object from FilePicker's file enumerator?");
-      if (domFile) {
-        newFiles.AppendElement(static_cast<File*>(domFile.get()));
+      if (domBlob) {
+        newFiles.AppendElement(static_cast<File*>(domBlob.get()));
       }
     }
   } else {
     MOZ_ASSERT(mode == static_cast<int16_t>(nsIFilePicker::modeOpen));
-    nsCOMPtr<nsIDOMFile> domFile;
-    nsresult rv = mFilePicker->GetDomfile(getter_AddRefs(domFile));
+    nsCOMPtr<nsISupports> tmp;
+    nsresult rv = mFilePicker->GetDomfile(getter_AddRefs(tmp));
     NS_ENSURE_SUCCESS(rv, rv);
-    if (domFile) {
-      newFiles.AppendElement(static_cast<File*>(domFile.get()));
+
+    nsCOMPtr<nsIDOMBlob> blob = do_QueryInterface(tmp);
+    if (blob) {
+      nsRefPtr<File> file = static_cast<Blob*>(blob.get())->ToFile();
+      newFiles.AppendElement(file);
     }
   }
 
diff --git a/dom/html/nsFormSubmission.cpp b/dom/html/nsFormSubmission.cpp
index 31e2d5f0579..93ae02ccc62 100644
--- a/dom/html/nsFormSubmission.cpp
+++ b/dom/html/nsFormSubmission.cpp
@@ -18,7 +18,6 @@
 #include "nsAttrValueInlines.h"
 #include "nsISaveAsCharset.h"
 #include "nsIFile.h"
-#include "nsIDOMFile.h"
 #include "nsDirectoryServiceDefs.h"
 #include "nsStringStream.h"
 #include "nsIURI.h"
diff --git a/dom/indexedDB/IDBMutableFile.cpp b/dom/indexedDB/IDBMutableFile.cpp
index b7dd0ce53cb..fd84c2ce315 100644
--- a/dom/indexedDB/IDBMutableFile.cpp
+++ b/dom/indexedDB/IDBMutableFile.cpp
@@ -27,7 +27,6 @@
 #include "nsContentUtils.h"
 #include "nsDebug.h"
 #include "nsError.h"
-#include "nsIDOMFile.h"
 #include "nsIPrincipal.h"
 
 namespace mozilla {
@@ -328,7 +327,7 @@ IDBMutableFile::GetFileId() const
   return mFileInfo->Id();
 }
 
-already_AddRefed<nsIDOMFile>
+already_AddRefed<File>
 IDBMutableFile::CreateFileObject(IDBFileHandle* aFileHandle,
                                  MetadataParameters* aMetadataParams)
 {
@@ -393,12 +392,10 @@ GetFileHelper::GetSuccessResult(JSContext* aCx,
 
   auto fileHandle = static_cast<IDBFileHandle*>(mFileHandle.get());
 
-  nsCOMPtr<nsIDOMFile> domFile =
+  nsRefPtr<File> domFile =
     mMutableFile->CreateFileObject(fileHandle, mParams);
 
-  nsresult rv =
-    nsContentUtils::WrapNative(aCx, domFile, &NS_GET_IID(nsIDOMFile), aVal);
-  if (NS_WARN_IF(NS_FAILED(rv))) {
+  if (!ToJSValue(aCx, domFile, aVal)) {
     return NS_ERROR_DOM_FILEHANDLE_UNKNOWN_ERR;
   }
 
diff --git a/dom/indexedDB/IDBMutableFile.h b/dom/indexedDB/IDBMutableFile.h
index ca26c78908c..45f78b9c67d 100644
--- a/dom/indexedDB/IDBMutableFile.h
+++ b/dom/indexedDB/IDBMutableFile.h
@@ -18,7 +18,6 @@
 #include "nsAutoPtr.h"
 #include "nsCycleCollectionParticipant.h"
 
-class nsIDOMFile;
 class nsPIDOMWindow;
 
 namespace mozilla {
@@ -28,6 +27,7 @@ class ErrorResult;
 namespace dom {
 
 class DOMRequest;
+class File;
 class MetadataParameters;
 
 namespace indexedDB {
@@ -83,7 +83,7 @@ public:
     return mFileInfo;
   }
 
-  already_AddRefed<nsIDOMFile>
+  already_AddRefed<File>
   CreateFileObject(IDBFileHandle* aFileHandle,
                    MetadataParameters* aMetadataParams);
 
diff --git a/dom/indexedDB/IDBTransaction.cpp b/dom/indexedDB/IDBTransaction.cpp
index c93b8ea9590..90d6f2820a5 100644
--- a/dom/indexedDB/IDBTransaction.cpp
+++ b/dom/indexedDB/IDBTransaction.cpp
@@ -17,7 +17,6 @@
 #include "mozilla/dom/DOMStringList.h"
 #include "mozilla/ipc/BackgroundChild.h"
 #include "nsIAppShell.h"
-#include "nsIDOMFile.h"
 #include "nsPIDOMWindow.h"
 #include "nsServiceManagerUtils.h"
 #include "nsTHashtable.h"
diff --git a/dom/indexedDB/test/file.js b/dom/indexedDB/test/file.js
index db0761910d3..ae63af38f99 100644
--- a/dom/indexedDB/test/file.js
+++ b/dom/indexedDB/test/file.js
@@ -94,12 +94,11 @@ function verifyBlob(blob1, blob2, fileId, blobReadHandler)
 {
   is(blob1 instanceof Components.interfaces.nsIDOMBlob, true,
      "Instance of nsIDOMBlob");
-  is(blob1 instanceof Components.interfaces.nsIDOMFile,
-     blob2 instanceof Components.interfaces.nsIDOMFile,
-     "Instance of nsIDOMFile");
+  is(blob1 instanceof File, blob2 instanceof File,
+     "Instance of DOM File");
   is(blob1.size, blob2.size, "Correct size");
   is(blob1.type, blob2.type, "Correct type");
-  if (blob2 instanceof Components.interfaces.nsIDOMFile) {
+  if (blob2 instanceof File) {
     is(blob1.name, blob2.name, "Correct name");
   }
   is(utils.getFileId(blob1), fileId, "Correct file id");
diff --git a/dom/interfaces/base/nsIDOMWindowUtils.idl b/dom/interfaces/base/nsIDOMWindowUtils.idl
index 22e545baec7..fcfb1250f12 100644
--- a/dom/interfaces/base/nsIDOMWindowUtils.idl
+++ b/dom/interfaces/base/nsIDOMWindowUtils.idl
@@ -39,8 +39,6 @@ interface nsIDOMStyleSheet;
 interface nsITransferable;
 interface nsIQueryContentEventResult;
 interface nsIDOMWindow;
-interface nsIDOMBlob;
-interface nsIDOMFile;
 interface nsIFile;
 interface nsIDOMClientRect;
 interface nsIURI;
@@ -51,7 +49,7 @@ interface nsIJSRAIIHelper;
 interface nsIContentPermissionRequest;
 interface nsIObserver;
 
-[scriptable, uuid(1a75c351-d115-4d51-94df-731dd1723a1f)]
+[scriptable, uuid(34a42cdc-7a04-4e71-8a5c-63e092fba58e)]
 interface nsIDOMWindowUtils : nsISupports {
 
   /**
@@ -1445,9 +1443,10 @@ interface nsIDOMWindowUtils : nsISupports {
                                   in AString value2);
 
   /**
-   * Wrap an nsIFile in an nsIDOMFile
+   * Wrap an nsIFile in an DOM File
+   * Returns a File object.
    */
-  nsIDOMFile wrapDOMFile(in nsIFile aFile);
+  nsISupports wrapDOMFile(in nsIFile aFile);
 
   /**
    * Get the type of the currently focused html input, if any.
diff --git a/dom/interfaces/html/nsIDOMHTMLCanvasElement.idl b/dom/interfaces/html/nsIDOMHTMLCanvasElement.idl
index 3ec838bb592..eaccc631b02 100644
--- a/dom/interfaces/html/nsIDOMHTMLCanvasElement.idl
+++ b/dom/interfaces/html/nsIDOMHTMLCanvasElement.idl
@@ -16,11 +16,10 @@
  */
 
 interface nsIDOMBlob;
-interface nsIDOMFile;
 interface nsIVariant;
 interface nsIInputStreamCallback;
 
-[uuid(8978d1c5-2981-4678-a1c3-b0b7bae04fbc)]
+[uuid(2c984658-2e7c-4774-8ac5-cf1b39f8bec3)]
 interface nsIDOMHTMLCanvasElement : nsISupports
 {
   attribute unsigned long width;
@@ -38,7 +37,8 @@ interface nsIDOMHTMLCanvasElement : nsISupports
   // Valid calls are
   // mozGetAsFile(name);              -- defaults to image/png
   // mozGetAsFile(name, type);        -- uses given type
-  nsIDOMFile mozGetAsFile(in DOMString name, [optional] in DOMString type);
+  // The return value is a File object.
+  nsISupports mozGetAsFile(in DOMString name, [optional] in DOMString type);
 
   // A Mozilla-only extension to get a canvas context backed by double-buffered
   // shared memory. Only privileged callers can call this.
diff --git a/dom/ipc/FilePickerParent.cpp b/dom/ipc/FilePickerParent.cpp
index e1d48ce97b1..3ee1189045a 100644
--- a/dom/ipc/FilePickerParent.cpp
+++ b/dom/ipc/FilePickerParent.cpp
@@ -8,7 +8,6 @@
 #include "nsComponentManagerUtils.h"
 #include "nsNetCID.h"
 #include "nsIDocument.h"
-#include "nsIDOMFile.h"
 #include "nsIDOMWindow.h"
 #include "nsIFile.h"
 #include "nsISimpleEnumerator.h"
diff --git a/dom/ipc/FilePickerParent.h b/dom/ipc/FilePickerParent.h
index 7a2f0e896ed..72cc41dc099 100644
--- a/dom/ipc/FilePickerParent.h
+++ b/dom/ipc/FilePickerParent.h
@@ -7,7 +7,6 @@
 #ifndef mozilla_dom_FilePickerParent_h
 #define mozilla_dom_FilePickerParent_h
 
-#include "nsIDOMFile.h"
 #include "nsIEventTarget.h"
 #include "nsIFilePicker.h"
 #include "nsCOMArray.h"
diff --git a/dom/media/MediaManager.cpp b/dom/media/MediaManager.cpp
index f33d1a2f936..e849a7c6cc5 100644
--- a/dom/media/MediaManager.cpp
+++ b/dom/media/MediaManager.cpp
@@ -113,6 +113,7 @@ GetMediaManagerLog()
 }
 #define LOG(msg) PR_LOG(GetMediaManagerLog(), PR_LOG_DEBUG, msg)
 
+using dom::File;
 using dom::MediaStreamConstraints;
 using dom::MediaTrackConstraintSet;
 using dom::MediaTrackConstraints;
@@ -264,53 +265,6 @@ private:
   nsRefPtr<MediaManager> mManager; // get ref to this when creating the runnable
 };
 
-/**
- * Invoke the "onSuccess" callback in content. The callback will take a
- * DOMBlob in the case of {picture:true}, and a MediaStream in the case of
- * {audio:true} or {video:true}. There is a constructor available for each
- * form. Do this only on the main thread.
- */
-class SuccessCallbackRunnable : public nsRunnable
-{
-public:
-  SuccessCallbackRunnable(
-    nsCOMPtr<nsIDOMGetUserMediaSuccessCallback>& aOnSuccess,
-    nsCOMPtr<nsIDOMGetUserMediaErrorCallback>& aOnFailure,
-    nsIDOMFile* aFile, uint64_t aWindowID)
-    : mFile(aFile)
-    , mWindowID(aWindowID)
-    , mManager(MediaManager::GetInstance())
-  {
-    mOnSuccess.swap(aOnSuccess);
-    mOnFailure.swap(aOnFailure);
-  }
-
-  NS_IMETHOD
-  Run()
-  {
-    // Only run if the window is still active.
-    NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
-
-    nsCOMPtr<nsIDOMGetUserMediaSuccessCallback> onSuccess = mOnSuccess.forget();
-    nsCOMPtr<nsIDOMGetUserMediaErrorCallback> onFailure = mOnFailure.forget();
-
-    if (!(mManager->IsWindowStillActive(mWindowID))) {
-      return NS_OK;
-    }
-    // This is safe since we're on main-thread, and the windowlist can only
-    // be invalidated from the main-thread (see OnNavigation)
-    onSuccess->OnSuccess(mFile);
-    return NS_OK;
-  }
-
-private:
-  nsCOMPtr<nsIDOMGetUserMediaSuccessCallback> mOnSuccess;
-  nsCOMPtr<nsIDOMGetUserMediaErrorCallback> mOnFailure;
-  nsCOMPtr<nsIDOMFile> mFile;
-  uint64_t mWindowID;
-  nsRefPtr<MediaManager> mManager; // get ref to this when creating the runnable
-};
-
 /**
  * Invoke the GetUserMediaDevices success callback. Wrapped in a runnable
  * so that it may be called on the main thread. The error callback is also
diff --git a/dom/media/webrtc/MediaEngineGonkVideoSource.h b/dom/media/webrtc/MediaEngineGonkVideoSource.h
index b072f193f5f..bfa12293f76 100644
--- a/dom/media/webrtc/MediaEngineGonkVideoSource.h
+++ b/dom/media/webrtc/MediaEngineGonkVideoSource.h
@@ -112,7 +112,7 @@ protected:
   mozilla::ReentrantMonitor mCallbackMonitor; // Monitor for camera callback handling
   // This is only modified on MainThread (AllocImpl and DeallocImpl)
   nsRefPtr<ICameraControl> mCameraControl;
-  nsCOMPtr<nsIDOMFile> mLastCapture;
+  nsRefPtr<dom::File> mLastCapture;
 
   android::sp<android::GonkCameraSource> mCameraSource;
 
diff --git a/dom/nfc/nsINfcContentHelper.idl b/dom/nfc/nsINfcContentHelper.idl
index 0454bf8636a..fc172fcad05 100644
--- a/dom/nfc/nsINfcContentHelper.idl
+++ b/dom/nfc/nsINfcContentHelper.idl
@@ -210,7 +210,7 @@ interface nsINfcContentHelper : nsISupports
    *
    * @param blob
    *        Raw data of the file to be sent. This object represents a file-like
-   *        (nsIDOMFile) object of immutable, raw data. The blob data needs
+   *        (DOM File) object of immutable, raw data. The blob data needs
    *        to be 'object wrapped' before calling this interface.
    *
    * @param sessionToken
diff --git a/dom/settings/SettingsDB.jsm b/dom/settings/SettingsDB.jsm
index e30273352db..492bff72bf4 100644
--- a/dom/settings/SettingsDB.jsm
+++ b/dom/settings/SettingsDB.jsm
@@ -8,7 +8,7 @@ let Cc = Components.classes;
 let Ci = Components.interfaces;
 let Cu = Components.utils;
 
-Cu.importGlobalProperties(['Blob']);
+Cu.importGlobalProperties(['Blob', 'File']);
 Cu.import("resource://gre/modules/Services.jsm");
 
 this.EXPORTED_SYMBOLS = ["SettingsDB", "SETTINGSDB_NAME", "SETTINGSSTORE_NAME"];
@@ -209,7 +209,7 @@ SettingsDB.prototype = {
       return "primitive";
     } else if (Array.isArray(aObject)) {
       return "array";
-    } else if (aObject instanceof Ci.nsIDOMFile) {
+    } else if (aObject instanceof File) {
       return "file";
     } else if (aObject instanceof Ci.nsIDOMBlob) {
       return "blob";
diff --git a/dom/settings/SettingsRequestManager.jsm b/dom/settings/SettingsRequestManager.jsm
index 0edac13d65c..92a015fe952 100644
--- a/dom/settings/SettingsRequestManager.jsm
+++ b/dom/settings/SettingsRequestManager.jsm
@@ -8,6 +8,8 @@ const Cc = Components.classes;
 const Ci = Components.interfaces;
 const Cu = Components.utils;
 
+Cu.importGlobalProperties(['File']);
+
 this.EXPORTED_SYMBOLS = ["SettingsRequestManager"];
 
 Cu.import("resource://gre/modules/SettingsDB.jsm");
@@ -245,7 +247,7 @@ let SettingsRequestManager = {
       if (!aValue || !aValue.constructor) {
         return false;
       }
-      return (aValue.constructor.name == "Date") || (aValue instanceof Ci.nsIDOMFile) ||
+      return (aValue.constructor.name == "Date") || (aValue instanceof File) ||
              (aValue instanceof Ci.nsIDOMBlob);
     }
     // We need to serialize settings objects, otherwise they can change between
diff --git a/dom/wifi/WifiCertService.cpp b/dom/wifi/WifiCertService.cpp
index 1ec5cf3c184..405ee4685dc 100644
--- a/dom/wifi/WifiCertService.cpp
+++ b/dom/wifi/WifiCertService.cpp
@@ -18,7 +18,7 @@
 #include "cert.h"
 #include "certdb.h"
 #include "CryptoTask.h"
-#include "nsIDOMFile.h"
+#include "nsIDOMBlob.h"
 #include "nsIWifiService.h"
 #include "nsNetUtil.h"
 #include "nsServiceManagerUtils.h"
diff --git a/js/xpconnect/src/XPCComponents.cpp b/js/xpconnect/src/XPCComponents.cpp
index 298b7e89069..659cd7c102f 100644
--- a/js/xpconnect/src/XPCComponents.cpp
+++ b/js/xpconnect/src/XPCComponents.cpp
@@ -28,7 +28,6 @@
 #include "mozilla/dom/StructuredCloneTags.h"
 #include "mozilla/dom/WindowBinding.h"
 #include "nsZipArchive.h"
-#include "nsIDOMFile.h"
 #include "nsIDOMFileList.h"
 #include "nsWindowMemoryReporter.h"
 #include "nsDOMClassInfo.h"
diff --git a/js/xpconnect/tests/chrome/test_cloneInto.xul b/js/xpconnect/tests/chrome/test_cloneInto.xul
index e5f58783b50..db4c61b0f3a 100644
--- a/js/xpconnect/tests/chrome/test_cloneInto.xul
+++ b/js/xpconnect/tests/chrome/test_cloneInto.xul
@@ -49,7 +49,7 @@
     if (Array.isArray(a))
       return 'array';
 
-    if (a instanceof Ci.nsIDOMFile)
+    if (a instanceof File)
       return 'file';
 
     if (a instanceof Ci.nsIDOMBlob)
diff --git a/js/xpconnect/tests/unit/component-blob.js b/js/xpconnect/tests/unit/component-blob.js
index fd528c86be7..7c50f7c925d 100644
--- a/js/xpconnect/tests/unit/component-blob.js
+++ b/js/xpconnect/tests/unit/component-blob.js
@@ -3,7 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
-Components.utils.importGlobalProperties(['Blob']);
+Components.utils.importGlobalProperties(['Blob', 'File']);
 
 const Cc = Components.classes;
 const Ci = Components.interfaces;
@@ -31,7 +31,7 @@ BlobComponent.prototype =
     // do some tests
     do_check_true(f1 instanceof Ci.nsIDOMBlob, "Should be a DOM Blob");
 
-    do_check_true(!(f1 instanceof Ci.nsIDOMFile), "Should not be a DOM File");
+    do_check_true(!(f1 instanceof File), "Should not be a DOM File");
 
     do_check_true(f1.type == "text/xml", "Wrong type");
 
diff --git a/js/xpconnect/tests/unit/component-file.js b/js/xpconnect/tests/unit/component-file.js
index 6a1b6ac8d77..d9c51d9f3fe 100644
--- a/js/xpconnect/tests/unit/component-file.js
+++ b/js/xpconnect/tests/unit/component-file.js
@@ -36,8 +36,8 @@ FileComponent.prototype =
     var f2 = new File(file);
 
     // do some tests
-    do_check_true(f1 instanceof Ci.nsIDOMFile, "Should be a DOM File");
-    do_check_true(f2 instanceof Ci.nsIDOMFile, "Should be a DOM File");
+    do_check_true(f1 instanceof File, "Should be a DOM File");
+    do_check_true(f2 instanceof File, "Should be a DOM File");
 
     do_check_true(f1.name == "xpcshell.ini", "Should be the right file");
     do_check_true(f2.name == "xpcshell.ini", "Should be the right file");
diff --git a/js/xpconnect/tests/unit/test_blob2.js b/js/xpconnect/tests/unit/test_blob2.js
index 2d39532f4dd..e031d0813c8 100644
--- a/js/xpconnect/tests/unit/test_blob2.js
+++ b/js/xpconnect/tests/unit/test_blob2.js
@@ -2,7 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-Components.utils.importGlobalProperties(['Blob']);
+Components.utils.importGlobalProperties(['Blob', 'File']);
 
 const Ci = Components.interfaces;
 
@@ -15,7 +15,7 @@ function run_test() {
   // do some tests
   do_check_true(f1 instanceof Ci.nsIDOMBlob, "Should be a DOM Blob");
 
-  do_check_true(!(f1 instanceof Ci.nsIDOMFile), "Should not be a DOM File");
+  do_check_true(!(f1 instanceof File), "Should not be a DOM File");
 
   do_check_true(f1.type == "text/xml", "Wrong type");
 
diff --git a/js/xpconnect/tests/unit/test_file2.js b/js/xpconnect/tests/unit/test_file2.js
index 7e52f8be853..375ba248854 100644
--- a/js/xpconnect/tests/unit/test_file2.js
+++ b/js/xpconnect/tests/unit/test_file2.js
@@ -21,8 +21,8 @@ function run_test() {
   var f2 = new File(file);
 
   // do some tests
-  do_check_true(f1 instanceof Ci.nsIDOMFile, "Should be a DOM File");
-  do_check_true(f2 instanceof Ci.nsIDOMFile, "Should be a DOM File");
+  do_check_true(f1 instanceof File, "Should be a DOM File");
+  do_check_true(f2 instanceof File, "Should be a DOM File");
 
   do_check_true(f1.name == "xpcshell.ini", "Should be the right file");
   do_check_true(f2.name == "xpcshell.ini", "Should be the right file");
diff --git a/toolkit/components/filepicker/nsFilePicker.js b/toolkit/components/filepicker/nsFilePicker.js
index 25156c4ac55..dc3ad70e4b9 100644
--- a/toolkit/components/filepicker/nsFilePicker.js
+++ b/toolkit/components/filepicker/nsFilePicker.js
@@ -93,7 +93,7 @@ nsFilePicker.prototype = {
   /* readonly attribute nsISimpleEnumerator files; */
   get files()  { return this.mFilesEnumerator; },
 
-  /* readonly attribute nsIDOMFile domfile; */
+  /* readonly attribute DOM File domfile; */
   get domfile()  {
     let enumerator = this.domfiles;
     return enumerator ? enumerator.mFiles[0] : null;
diff --git a/toolkit/modules/PropertyListUtils.jsm b/toolkit/modules/PropertyListUtils.jsm
index 8602a4e4651..436caef9fe0 100644
--- a/toolkit/modules/PropertyListUtils.jsm
+++ b/toolkit/modules/PropertyListUtils.jsm
@@ -83,7 +83,7 @@ this.PropertyListUtils = Object.freeze({
    *        The reaon for failure is reported to the Error Console.
    */
   read: function PLU_read(aFile, aCallback) {
-    if (!(aFile instanceof Ci.nsILocalFile || aFile instanceof Ci.nsIDOMFile))
+    if (!(aFile instanceof Ci.nsILocalFile || aFile instanceof File))
       throw new Error("aFile is not a file object");
     if (typeof(aCallback) != "function")
       throw new Error("Invalid value for aCallback");
diff --git a/widget/nsBaseFilePicker.cpp b/widget/nsBaseFilePicker.cpp
index 7576b6cd498..37aec317d8e 100644
--- a/widget/nsBaseFilePicker.cpp
+++ b/widget/nsBaseFilePicker.cpp
@@ -96,7 +96,7 @@ public:
       return NS_ERROR_FAILURE;
     }
 
-    nsCOMPtr<nsIDOMFile> domFile = File::CreateFromFile(mParent, localFile);
+    nsCOMPtr<nsIDOMBlob> domFile = File::CreateFromFile(mParent, localFile);
     domFile.forget(aResult);
     return NS_OK;
   }
@@ -311,7 +311,7 @@ nsBaseFilePicker::GetMode(int16_t* aMode)
 }
 
 NS_IMETHODIMP
-nsBaseFilePicker::GetDomfile(nsIDOMFile** aDomfile)
+nsBaseFilePicker::GetDomfile(nsISupports** aDomfile)
 {
   nsCOMPtr<nsIFile> localFile;
   nsresult rv = GetFile(getter_AddRefs(localFile));
@@ -322,7 +322,7 @@ nsBaseFilePicker::GetDomfile(nsIDOMFile** aDomfile)
     return NS_OK;
   }
 
-  nsRefPtr<File> domFile = File::CreateFromFile(mParent, localFile);
+  nsCOMPtr<nsIDOMBlob> domFile = File::CreateFromFile(mParent, localFile);
   domFile.forget(aDomfile);
   return NS_OK;
 }
diff --git a/widget/nsBaseFilePicker.h b/widget/nsBaseFilePicker.h
index 1a470674631..b192a162573 100644
--- a/widget/nsBaseFilePicker.h
+++ b/widget/nsBaseFilePicker.h
@@ -37,7 +37,7 @@ public:
   NS_IMETHOD SetAddToRecentDocs(bool aFlag);
   NS_IMETHOD GetMode(int16_t *aMode);
 
-  NS_IMETHOD GetDomfile(nsIDOMFile** aDomfile);
+  NS_IMETHOD GetDomfile(nsISupports** aDomfile);
   NS_IMETHOD GetDomfiles(nsISimpleEnumerator** aDomfiles);
 
 protected:
diff --git a/widget/nsFilePickerProxy.cpp b/widget/nsFilePickerProxy.cpp
index 54a73aaa099..b1eb2911de3 100644
--- a/widget/nsFilePickerProxy.cpp
+++ b/widget/nsFilePickerProxy.cpp
@@ -165,7 +165,7 @@ nsFilePickerProxy::Recv__delete__(const MaybeInputFiles& aFiles,
       nsRefPtr<File> file = File::Create(mParent, blobImpl);
       MOZ_ASSERT(file);
 
-      mDomfiles.AppendObject(file);
+      mDomfiles.AppendElement(file);
     }
   }
 
@@ -178,7 +178,7 @@ nsFilePickerProxy::Recv__delete__(const MaybeInputFiles& aFiles,
 }
 
 NS_IMETHODIMP
-nsFilePickerProxy::GetDomfile(nsIDOMFile** aDomfile)
+nsFilePickerProxy::GetDomfile(nsISupports** aDomfile)
 {
   *aDomfile = nullptr;
   if (mDomfiles.IsEmpty()) {
@@ -186,13 +186,55 @@ nsFilePickerProxy::GetDomfile(nsIDOMFile** aDomfile)
   }
 
   MOZ_ASSERT(mDomfiles.Length() == 1);
-  nsCOMPtr<nsIDOMFile> domfile = mDomfiles[0];
-  domfile.forget(aDomfile);
+  nsCOMPtr<nsIDOMBlob> blob = mDomfiles[0].get();
+  blob.forget(aDomfile);
   return NS_OK;
 }
 
+namespace {
+
+class SimpleEnumerator final : public nsISimpleEnumerator
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  explicit SimpleEnumerator(const nsTArray<nsRefPtr<File>>& aFiles)
+    : mFiles(aFiles)
+    , mIndex(0)
+  {}
+
+  NS_IMETHOD
+  HasMoreElements(bool* aRetvalue) override
+  {
+    MOZ_ASSERT(aRetvalue);
+    *aRetvalue = mFiles.Length() >= mIndex;
+    return NS_OK;
+  }
+
+  NS_IMETHOD
+  GetNext(nsISupports** aSupports) override
+  {
+    nsCOMPtr<nsIDOMBlob> blob = mFiles[mIndex++].get();
+    blob.forget(aSupports);
+    return NS_OK;
+  }
+
+private:
+  ~SimpleEnumerator()
+  {}
+
+  nsTArray<nsRefPtr<File>> mFiles;
+  uint32_t mIndex;
+};
+
+NS_IMPL_ISUPPORTS(SimpleEnumerator, nsISimpleEnumerator)
+
+} // anonymous namespace
+
 NS_IMETHODIMP
 nsFilePickerProxy::GetDomfiles(nsISimpleEnumerator** aDomfiles)
 {
-  return NS_NewArrayEnumerator(aDomfiles, mDomfiles);
+  nsRefPtr<SimpleEnumerator> enumerator = new SimpleEnumerator(mDomfiles);
+  enumerator.forget(aDomfiles);
+  return NS_OK;
 }
diff --git a/widget/nsFilePickerProxy.h b/widget/nsFilePickerProxy.h
index 63c50fee273..aaba9857772 100644
--- a/widget/nsFilePickerProxy.h
+++ b/widget/nsFilePickerProxy.h
@@ -18,6 +18,12 @@ class nsIWidget;
 class nsIFile;
 class nsPIDOMWindow;
 
+namespace mozilla {
+namespace dom {
+class File;
+}
+}
+
 /**
   This class creates a proxy file picker to be used in content processes.
   The file picker just collects the initialization data and when Show() is
@@ -45,7 +51,7 @@ public:
     NS_IMETHODIMP GetFileURL(nsIURI** aFileURL) override;
     NS_IMETHODIMP GetFiles(nsISimpleEnumerator** aFiles) override;
 
-    NS_IMETHODIMP GetDomfile(nsIDOMFile** aFile) override;
+    NS_IMETHODIMP GetDomfile(nsISupports** aFile) override;
     NS_IMETHODIMP GetDomfiles(nsISimpleEnumerator** aFiles) override;
 
     NS_IMETHODIMP Show(int16_t* aReturn) override;
@@ -59,7 +65,7 @@ private:
     ~nsFilePickerProxy();
     void InitNative(nsIWidget*, const nsAString&) override;
 
-    nsCOMArray<nsIDOMFile> mDomfiles;
+    nsTArray<nsRefPtr<mozilla::dom::File>> mDomfiles;
     nsCOMPtr<nsIFilePickerShownCallback> mCallback;
 
     int16_t   mSelectedType;
diff --git a/widget/nsIFilePicker.idl b/widget/nsIFilePicker.idl
index 5a0f1d4475f..c51db99a336 100644
--- a/widget/nsIFilePicker.idl
+++ b/widget/nsIFilePicker.idl
@@ -8,7 +8,6 @@
 
 interface nsIFile;
 interface nsIURI;
-interface nsIDOMFile;
 interface nsIDOMWindow;
 interface nsISimpleEnumerator;
 
@@ -24,7 +23,7 @@ interface nsIFilePickerShownCallback : nsISupports
   void done(in short aResult);
 };
 
-[scriptable, uuid(f93509a0-0434-11e3-8ffd-0800200c9a66)]
+[scriptable, uuid(9840d564-42c8-4d78-9a4d-71002343c918)]
 interface nsIFilePicker : nsISupports
 {
   const short modeOpen        = 0;              // Load a file or directory
@@ -143,11 +142,11 @@ interface nsIFilePicker : nsISupports
   readonly attribute nsISimpleEnumerator files;
 
  /**
-  * Get the nsIDOMFile for the file.
+  * Get the DOM File for the file.
   *
   * @return Returns the file currently selected as File
   */
-  readonly attribute nsIDOMFile domfile;
+  readonly attribute nsISupports domfile;
 
  /**
   * Get the enumerator for the selected files