Bug 1006957 - Handle buffer ownership between SurfaceStream and CanvasClient r=nical

gfx/layers/client/CanvasClient.cpp

@@ -5,6 +5,7 @@
 
 #include "mozilla/layers/CanvasClient.h"
 #include "ClientCanvasLayer.h"          // for ClientCanvasLayer
+#include "CompositorChild.h"            // for CompositorChild
 #include "GLContext.h"                  // for GLContext
 #include "GLScreenBuffer.h"             // for GLScreenBuffer
 #include "SurfaceStream.h"              // for SurfaceStream
@@ -172,6 +173,17 @@ CanvasClientSurfaceStream::Update(gfx::IntSize aSize, ClientCanvasLayer* aLayer)
     if (grallocTextureClient->GetIPDLActor()) {
       GetForwarder()->UseTexture(this, grallocTextureClient);
     }
+
+    if (mBuffer && CompositorChild::ChildProcessHasCompositor()) {
+      // remove old buffer from CompositableHost
+      RefPtr<AsyncTransactionTracker> tracker = new RemoveTextureFromCompositableTracker(this);
+      // Hold TextureClient until transaction complete.
+      tracker->SetTextureClient(mBuffer);
+      mBuffer->SetRemoveFromCompositableTracker(tracker);
+      // RemoveTextureFromCompositableAsync() expects CompositorChild's presence.
+      GetForwarder()->RemoveTextureFromCompositableAsync(tracker, this, mBuffer);
+    }
+    mBuffer = grallocTextureClient;
 #else
     printf_stderr("isCrossProcess, but not MOZ_WIDGET_GONK! Someone needs to write some code!");
     MOZ_ASSERT(false);