Bug 1345403 part 2 - Mark element tainted when DrawImage is used; r=jwwang,mattwoodrow

Mark video element as tainted (stored on the decoder owned by video element) when the video is used as source to drawImage() on canvas.

MozReview-Commit-ID: HdciVwhqPu3

--HG--
extra : rebase_source : b26c257afaaabdd6346a5421988d95e82281d7ef
extra : source : 149234329b62015dfd2e954030c23bf9c6b1d55e

dom/html/HTMLMediaElement.cpp

@@ -1527,6 +1527,26 @@ HTMLMediaElement::SetVisible(bool aVisible)
   mDecoder->SetForcedHidden(!aVisible);
 }
 
+layers::Image*
+HTMLMediaElement::GetCurrentImage()
+{
+  // Mark the decoder owned by the element as tainted so that the
+  // suspend-vide-decoder is suspended.
+  mHasSuspendTaint = true;
+  if (mDecoder) {
+    mDecoder->SetSuspendTaint(true);
+  }
+
+  // TODO: In bug 1345404, handle case when video decoder is already suspended.
+  ImageContainer* container = GetImageContainer();
+  if (!container) {
+    return nullptr;
+  }
+
+  AutoLockImage lockImage(container);
+  return lockImage.GetImage();
+}
+
 already_AddRefed<DOMMediaStream>
 HTMLMediaElement::GetSrcObject() const
 {
@@ -3692,6 +3712,7 @@ HTMLMediaElement::HTMLMediaElement(already_AddRefed<mozilla::dom::NodeInfo>& aNo
     mFirstFrameLoaded(false),
     mDefaultPlaybackStartPosition(0.0),
     mIsAudioTrackAudible(false),
+    mHasSuspendTaint(false),
     mVisibilityState(Visibility::APPROXIMATELY_NONVISIBLE),
     mErrorSink(new ErrorSink(this)),
     mAudioChannelWrapper(new AudioChannelAgentCallback(this, mAudioChannel))
@@ -4689,6 +4710,8 @@ nsresult HTMLMediaElement::FinishDecoderSetup(MediaDecoder* aDecoder,
   if (mPreloadAction == HTMLMediaElement::PRELOAD_METADATA) {
     mDecoder->SetMinimizePrerollUntilPlaybackStarts();
   }
+  // Notify the decoder of suspend taint.
+  mDecoder->SetSuspendTaint(mHasSuspendTaint);
 
   // Update decoder principal before we start decoding, since it
   // can affect how we feed data to MediaStreams

dom/html/HTMLMediaElement.h

@@ -619,6 +619,14 @@ public:
 
   void SetVisible(bool aVisible);
 
+  // Synchronously, return the next video frame and mark the element unable to
+  // participate in decode suspending.
+  //
+  // This function is synchronous for cases where decoding has been suspended
+  // and JS needs a frame to use in, eg., nsLayoutUtils::SurfaceFromElement()
+  // via drawImage().
+  layers::Image* GetCurrentImage();
+
   already_AddRefed<DOMMediaStream> GetSrcObject() const;
   void SetSrcObject(DOMMediaStream& aValue);
   void SetSrcObject(DOMMediaStream* aValue);
@@ -1714,6 +1722,10 @@ private:
   // True if the audio track is not silent.
   bool mIsAudioTrackAudible;
 
+  // True if media element has been marked as 'tainted' and can't
+  // participate in video decoder suspending.
+  bool mHasSuspendTaint;
+
   Visibility mVisibilityState;
 
   UniquePtr<ErrorSink> mErrorSink;

layout/base/nsLayoutUtils.cpp

@@ -7337,13 +7337,8 @@ nsLayoutUtils::SurfaceFromElement(HTMLVideoElement* aElement,
   if (!principal)
     return result;
 
-  ImageContainer* container = aElement->GetImageContainer();
-  if (!container)
-    return result;
+  result.mLayersImage = aElement->GetCurrentImage();
 
-  AutoLockImage lockImage(container);
-
-  result.mLayersImage = lockImage.GetImage();
   if (!result.mLayersImage)
     return result;