Bug 1212323: P2. Have IsVideoAccelerated return a Promise. r=cpearce

dom/base/nsDOMWindowUtils.cpp

@@ -106,6 +106,7 @@
 #include "HTMLImageElement.h"
 #include "mozilla/css/ImageLoader.h"
 #include "mozilla/layers/APZCTreeManager.h" // for layers::ZoomToRectBehavior
+#include "mozilla/dom/Promise.h"
 
 #ifdef XP_WIN
 #undef GetClassName
@@ -2150,26 +2151,29 @@ nsDOMWindowUtils::GetLayerManagerRemote(bool* retval)
 }
 
 NS_IMETHODIMP
-nsDOMWindowUtils::GetSupportsHardwareH264Decoding(nsAString& aRetval)
+nsDOMWindowUtils::GetSupportsHardwareH264Decoding(JS::MutableHandle<JS::Value> aPromise)
 {
+  nsCOMPtr<nsPIDOMWindow> window = do_QueryReferent(mWindow);
+  NS_ENSURE_STATE(window);
+  nsCOMPtr<nsIGlobalObject> parentObject = do_QueryInterface(window);
+  NS_ENSURE_STATE(parentObject);
 #ifdef MOZ_FMP4
   nsCOMPtr<nsIWidget> widget = GetWidget();
-  if (!widget)
-    return NS_ERROR_FAILURE;
-
+  NS_ENSURE_STATE(widget);
   LayerManager *mgr = widget->GetLayerManager();
-  if (!mgr)
-    return NS_ERROR_FAILURE;
-
-  nsCString failureReason;
-  if (MP4Decoder::IsVideoAccelerated(mgr->GetCompositorBackendType(), failureReason)) {
-    aRetval.AssignLiteral("Yes");
-  } else {
-    aRetval.AssignLiteral("No; ");
-    AppendUTF8toUTF16(failureReason, aRetval);
-  }
+  NS_ENSURE_STATE(mgr);
+  RefPtr<Promise> promise =
+    MP4Decoder::IsVideoAccelerated(mgr->GetCompositorBackendType(), parentObject);
+  NS_ENSURE_STATE(promise);
+  aPromise.setObject(*promise->GetWrapper());
 #else
-  aRetval.AssignLiteral("No; Compiled without MP4 support.");
+  ErrorResult rv;
+  RefPtr<Promise> promise = Promise::Create(parentObject, rv);
+  if (rv.Failed()) {
+    return rv.StealNSResult();
+  }
+  promise.MaybeResolve(NS_LITERAL_STRING("No; Compiled without MP4 support."));
+  aPromise.setObject(*promise->GetWrapper());
 #endif
   return NS_OK;
 }

dom/interfaces/base/nsIDOMWindowUtils.idl

@@ -49,7 +49,7 @@ interface nsIJSRAIIHelper;
 interface nsIContentPermissionRequest;
 interface nsIObserver;
 
-[scriptable, uuid(ca6a458c-82e7-4979-886e-6d214eac6f0b)]
+[scriptable, uuid(46b44e33-13c2-4eb3-bf80-76a4e0857ccc)]
 interface nsIDOMWindowUtils : nsISupports {
 
   /**
@@ -1334,11 +1334,12 @@ interface nsIDOMWindowUtils : nsISupports {
   readonly attribute boolean layerManagerRemote;
 
   /**
-   * True if we can initialize a hardware-backed h264 decoder for a simple
-   * test video, does not mean that all h264 video decoding will be done
+   * Returns a Promise that will be resolved with a string once the capabilities
+   * of the h264 decoder have been determined.
+   * Success does not mean that all h264 video decoding will be done
    * in hardware.
    */
-  readonly attribute AString supportsHardwareH264Decoding;
+  readonly attribute jsval supportsHardwareH264Decoding;
 
   /**
    * Record (and return) frame-intervals for frames which were presented

dom/media/fmp4/MP4Decoder.cpp

@@ -213,7 +213,8 @@ static const uint8_t sTestH264ExtraData[] = {
 
 static already_AddRefed<MediaDataDecoder>
 CreateTestH264Decoder(layers::LayersBackend aBackend,
-                      VideoInfo& aConfig)
+                      VideoInfo& aConfig,
+                      FlushableTaskQueue* aTaskQueue)
 {
   aConfig.mMimeType = "video/avc";
   aConfig.mId = 1;
@@ -229,23 +230,63 @@ CreateTestH264Decoder(layers::LayersBackend aBackend,
 
   RefPtr<PDMFactory> platform = new PDMFactory();
   RefPtr<MediaDataDecoder> decoder(
-    platform->CreateDecoder(aConfig, nullptr, nullptr, aBackend, nullptr));
+    platform->CreateDecoder(aConfig, aTaskQueue, nullptr, aBackend, nullptr));
 
   return decoder.forget();
 }
 
-/* static */ bool
-MP4Decoder::IsVideoAccelerated(layers::LayersBackend aBackend, nsACString& aFailureReason)
+/* static */ already_AddRefed<dom::Promise>
+MP4Decoder::IsVideoAccelerated(layers::LayersBackend aBackend, nsIGlobalObject* aParent)
 {
-  VideoInfo config;
-  RefPtr<MediaDataDecoder> decoder(CreateTestH264Decoder(aBackend, config));
-  if (!decoder) {
-    aFailureReason.AssignLiteral("Failed to create H264 decoder");
-    return false;
+  MOZ_ASSERT(NS_IsMainThread());
+
+  ErrorResult rv;
+  RefPtr<dom::Promise> promise;
+  promise = dom::Promise::Create(aParent, rv);
+  if (rv.Failed()) {
+    rv.SuppressException();
+    return nullptr;
   }
-  bool result = decoder->IsHardwareAccelerated(aFailureReason);
-  decoder->Shutdown();
-  return result;
+
+  RefPtr<FlushableTaskQueue> taskQueue =
+    new FlushableTaskQueue(GetMediaThreadPool(MediaThreadType::PLATFORM_DECODER));
+  VideoInfo config;
+  RefPtr<MediaDataDecoder> decoder(CreateTestH264Decoder(aBackend, config, taskQueue));
+  if (!decoder) {
+    taskQueue->BeginShutdown();
+    taskQueue->AwaitShutdownAndIdle();
+    promise->MaybeResolve(NS_LITERAL_STRING("No; Failed to create H264 decoder"));
+    return promise.forget();
+  }
+
+  decoder->Init()
+    ->Then(AbstractThread::MainThread(), __func__,
+           [promise, decoder, taskQueue] (TrackInfo::TrackType aTrack) {
+             nsCString failureReason;
+             bool ok = decoder->IsHardwareAccelerated(failureReason);
+             nsAutoString result;
+             if (ok) {
+               result.AssignLiteral("Yes");
+             } else {
+               result.AssignLiteral("No");
+               if (failureReason.Length()) {
+                 result.AppendLiteral("; ");
+                 AppendUTF8toUTF16(failureReason, result);
+               }
+             }
+             decoder->Shutdown();
+             taskQueue->BeginShutdown();
+             taskQueue->AwaitShutdownAndIdle();
+             promise->MaybeResolve(result);
+           },
+           [promise, decoder, taskQueue] (MediaDataDecoder::DecoderFailureReason aResult) {
+             decoder->Shutdown();
+             taskQueue->BeginShutdown();
+             taskQueue->AwaitShutdownAndIdle();
+             promise->MaybeResolve(NS_LITERAL_STRING("No; Failed to initialize H264 decoder"));
+           });
+
+  return promise.forget();
 }
 
 void

dom/media/fmp4/MP4Decoder.h

@@ -8,6 +8,7 @@
 
 #include "MediaDecoder.h"
 #include "MediaFormatReader.h"
+#include "mozilla/dom/Promise.h"
 
 namespace mozilla {
 
@@ -38,7 +39,8 @@ public:
   // Returns true if the MP4 backend is preffed on.
   static bool IsEnabled();
 
-  static bool IsVideoAccelerated(layers::LayersBackend aBackend, nsACString& aReason);
+  static already_AddRefed<dom::Promise>
+  IsVideoAccelerated(layers::LayersBackend aBackend, nsIGlobalObject* aParent);
 
   void GetMozDebugReaderData(nsAString& aString) override;