diff --git a/image/ImageCacheKey.cpp b/image/ImageCacheKey.cpp
new file mode 100644
index 00000000000..96bdaec93f9
--- /dev/null
+++ b/image/ImageCacheKey.cpp
@@ -0,0 +1,70 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * 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/. */
+
+#include "ImageCacheKey.h"
+
+#include "mozilla/Move.h"
+#include "File.h"
+#include "ImageURL.h"
+#include "nsHostObjectProtocolHandler.h"
+#include "nsString.h"
+
+namespace mozilla {
+
+using namespace dom;
+
+namespace image {
+
+ImageCacheKey::ImageCacheKey(nsIURI* aURI)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aURI);
+
+  bool isChrome;
+  mIsChrome = NS_SUCCEEDED(aURI->SchemeIs("chrome", &isChrome)) && isChrome;
+
+  aURI->GetSpec(mSpec);
+  mHash = ComputeHash(mSpec);
+}
+
+ImageCacheKey::ImageCacheKey(ImageURL* aURI)
+{
+  MOZ_ASSERT(aURI);
+
+  bool isChrome;
+  mIsChrome = NS_SUCCEEDED(aURI->SchemeIs("chrome", &isChrome)) && isChrome;
+
+  aURI->GetSpec(mSpec);
+  mHash = ComputeHash(mSpec);
+}
+
+ImageCacheKey::ImageCacheKey(const ImageCacheKey& aOther)
+  : mSpec(aOther.mSpec)
+  , mHash(aOther.mHash)
+  , mIsChrome(aOther.mIsChrome)
+{ }
+
+ImageCacheKey::ImageCacheKey(ImageCacheKey&& aOther)
+  : mSpec(Move(aOther.mSpec))
+  , mHash(aOther.mHash)
+  , mIsChrome(aOther.mIsChrome)
+{ }
+
+bool
+ImageCacheKey::operator==(const ImageCacheKey& aOther) const
+{
+  return mSpec == aOther.mSpec;
+}
+
+/* static */ uint32_t
+ImageCacheKey::ComputeHash(const nsACString& aSpec)
+{
+  // Since we frequently call Hash() several times in a row on the same
+  // ImageCacheKey, as an optimization we compute our hash once and store it.
+  return HashString(aSpec);
+}
+
+} // namespace image
+} // namespace mozilla
diff --git a/image/ImageCacheKey.h b/image/ImageCacheKey.h
new file mode 100644
index 00000000000..985f49d8fc7
--- /dev/null
+++ b/image/ImageCacheKey.h
@@ -0,0 +1,55 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * 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/. */
+
+/**
+ * ImageCacheKey is the key type for the image cache (see imgLoader.h).
+ */
+
+#ifndef mozilla_image_src_ImageCacheKey_h
+#define mozilla_image_src_ImageCacheKey_h
+
+class nsIURI;
+
+namespace mozilla {
+namespace image {
+
+class ImageURL;
+
+/**
+ * An ImageLib cache entry key.
+ *
+ * We key the cache on the initial URI (before any redirects), with some
+ * canonicalization applied. See ComputeHash() for the details.
+ */
+class ImageCacheKey final
+{
+public:
+  explicit ImageCacheKey(nsIURI* aURI);
+  explicit ImageCacheKey(ImageURL* aURI);
+
+  ImageCacheKey(const ImageCacheKey& aOther);
+  ImageCacheKey(ImageCacheKey&& aOther);
+
+  bool operator==(const ImageCacheKey& aOther) const;
+  uint32_t Hash() const { return mHash; }
+
+  /// A weak pointer to the URI spec for this cache entry. For logging only.
+  const char* Spec() const { return mSpec.get(); }
+
+  /// Is this cache entry for a chrome image?
+  bool IsChrome() const { return mIsChrome; }
+
+private:
+  static uint32_t ComputeHash(const nsACString& aSpec);
+
+  nsCString mSpec;
+  uint32_t mHash;
+  bool mIsChrome;
+};
+
+} // namespace image
+} // namespace mozilla
+
+#endif // mozilla_image_src_ImageCacheKey_h
diff --git a/image/imgLoader.cpp b/image/imgLoader.cpp
index d685798664f..28ee443e933 100644
--- a/image/imgLoader.cpp
+++ b/image/imgLoader.cpp
@@ -1100,60 +1100,6 @@ imgCacheExpirationTracker::NotifyExpired(imgCacheEntry* entry)
 }
 
 
-///////////////////////////////////////////////////////////////////////////////
-// ImageCacheKey
-///////////////////////////////////////////////////////////////////////////////
-
-ImageCacheKey::ImageCacheKey(nsIURI* aURI)
-{
-  MOZ_ASSERT(NS_IsMainThread());
-  MOZ_ASSERT(aURI);
-
-  bool isChrome;
-  mIsChrome = NS_SUCCEEDED(aURI->SchemeIs("chrome", &isChrome)) && isChrome;
-
-  aURI->GetSpec(mSpec);
-  mHash = ComputeHash(mSpec);
-}
-
-ImageCacheKey::ImageCacheKey(ImageURL* aURI)
-{
-  MOZ_ASSERT(aURI);
-
-  bool isChrome;
-  mIsChrome = NS_SUCCEEDED(aURI->SchemeIs("chrome", &isChrome)) && isChrome;
-
-  aURI->GetSpec(mSpec);
-  mHash = ComputeHash(mSpec);
-}
-
-ImageCacheKey::ImageCacheKey(const ImageCacheKey& aOther)
-  : mSpec(aOther.mSpec)
-  , mHash(aOther.mHash)
-  , mIsChrome(aOther.mIsChrome)
-{ }
-
-ImageCacheKey::ImageCacheKey(ImageCacheKey&& aOther)
-  : mSpec(Move(aOther.mSpec))
-  , mHash(aOther.mHash)
-  , mIsChrome(aOther.mIsChrome)
-{ }
-
-bool
-ImageCacheKey::operator==(const ImageCacheKey& aOther) const
-{
-  return mSpec == aOther.mSpec;
-}
-
-/* static */ uint32_t
-ImageCacheKey::ComputeHash(const nsACString& aSpec)
-{
-  // Since we frequently call Hash() several times in a row on the same
-  // ImageCacheKey, as an optimization we compute our hash once and store it.
-  return HashString(aSpec);
-}
-
-
 ///////////////////////////////////////////////////////////////////////////////
 // imgLoader
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/image/imgLoader.h b/image/imgLoader.h
index 8f13aaa6c96..776b32e6978 100644
--- a/image/imgLoader.h
+++ b/image/imgLoader.h
@@ -17,6 +17,7 @@
 #include "nsRefPtrHashtable.h"
 #include "nsExpirationTracker.h"
 #include "nsAutoPtr.h"
+#include "ImageCacheKey.h"
 #include "imgRequest.h"
 #include "nsIProgressEventSink.h"
 #include "nsIChannel.h"
@@ -214,38 +215,6 @@ enum class AcceptedMimeTypes : uint8_t {
   IMAGES_AND_DOCUMENTS,
 };
 
-/**
- * An ImageLib cache entry key.
- *
- * We key the cache on the initial URI (before any redirects), with some
- * canonicalization applied. See ComputeHash() for the details.
- */
-class ImageCacheKey final
-{
-public:
-  explicit ImageCacheKey(nsIURI* aURI);
-  explicit ImageCacheKey(mozilla::image::ImageURL* aURI);
-
-  ImageCacheKey(const ImageCacheKey& aOther);
-  ImageCacheKey(ImageCacheKey&& aOther);
-
-  bool operator==(const ImageCacheKey& aOther) const;
-  uint32_t Hash() const { return mHash; }
-
-  /// A weak pointer to the URI spec for this cache entry. For logging only.
-  const char* Spec() const { return mSpec.get(); }
-
-  /// Is this cache entry for a chrome image?
-  bool IsChrome() const { return mIsChrome; }
-
-private:
-  static uint32_t ComputeHash(const nsACString& aSpec);
-
-  nsCString mSpec;
-  uint32_t mHash;
-  bool mIsChrome;
-};
-
 class imgLoader final : public imgILoader,
                         public nsIContentSniffer,
                         public imgICache,
@@ -255,6 +224,7 @@ class imgLoader final : public imgILoader,
   virtual ~imgLoader();
 
 public:
+  typedef mozilla::image::ImageCacheKey ImageCacheKey;
   typedef mozilla::image::ImageURL ImageURL;
   typedef nsRefPtrHashtable<nsGenericHashKey<ImageCacheKey>,
                             imgCacheEntry> imgCacheTable;
diff --git a/image/moz.build b/image/moz.build
index 29b33714fc2..299fe09ddd2 100644
--- a/image/moz.build
+++ b/image/moz.build
@@ -34,6 +34,7 @@ XPIDL_SOURCES += [
 XPIDL_MODULE = 'imglib2'
 
 EXPORTS += [
+    'ImageCacheKey.h',
     'ImageLogging.h',
     'ImageOps.h',
     'ImageRegion.h',
@@ -53,6 +54,7 @@ UNIFIED_SOURCES += [
     'FrameAnimator.cpp',
     'FrozenImage.cpp',
     'Image.cpp',
+    'ImageCacheKey.cpp',
     'ImageFactory.cpp',
     'ImageMetadata.cpp',
     'ImageOps.cpp',