Bug 1119019 - Avoid destroying a SharedSurface before its TextureClient/Host pair. r=sotaro

gfx/layers/client/CanvasClient.cpp

@@ -403,5 +403,20 @@ CanvasClientSharedSurface::Update(gfx::IntSize aSize, ClientCanvasLayer* aLayer)
   forwarder->UseTexture(this, mFrontTex);
 }
 
+void
+CanvasClientSharedSurface::ClearSurfaces()
+{
+  if (mFrontTex && (mFront || mPrevFront)) {
+    // Force a synchronous destruction so that the TextureHost does not
+    // outlive the SharedSurface. This won't be needed once TextureClient/Host
+    // and SharedSurface are merged.
+    mFrontTex->ForceRemove(true /* sync */);
+    mFrontTex = nullptr;
+  }
+  // It is important to destroy the SharedSurface *after* the TextureClient.
+  mFront = nullptr;
+  mPrevFront = nullptr;
+}
+
 }
 }

gfx/layers/client/CanvasClient.h

@@ -119,25 +119,30 @@ private:
 
   RefPtr<TextureClient> mFrontTex;
 
+  void ClearSurfaces();
+
 public:
   CanvasClientSharedSurface(CompositableForwarder* aLayerForwarder,
                             TextureFlags aFlags);
 
+  ~CanvasClientSharedSurface()
+  {
+    ClearSurfaces();
+  }
+
   virtual TextureInfo GetTextureInfo() const MOZ_OVERRIDE {
     return TextureInfo(CompositableType::IMAGE);
   }
 
   virtual void Clear() MOZ_OVERRIDE {
-    mFront = nullptr;
-    mPrevFront = nullptr;
-    mFrontTex = nullptr;
+    ClearSurfaces();
   }
 
   virtual void Update(gfx::IntSize aSize,
                       ClientCanvasLayer* aLayer) MOZ_OVERRIDE;
 
   virtual void OnDetach() MOZ_OVERRIDE {
-    CanvasClientSharedSurface::Clear();
+    ClearSurfaces();
   }
 };
 

gfx/layers/client/TextureClient.cpp

@@ -503,10 +503,10 @@ TextureClient::KeepUntilFullDeallocation(KeepAlive* aKeep)
   mActor->mKeep = aKeep;
 }
 
-void TextureClient::ForceRemove()
+void TextureClient::ForceRemove(bool sync)
 {
   if (mValid && mActor) {
-    if (GetFlags() & TextureFlags::DEALLOCATE_CLIENT) {
+    if (sync || GetFlags() & TextureFlags::DEALLOCATE_CLIENT) {
       MOZ_PERFORMANCE_WARNING("gfx", "TextureClient/Host pair requires synchronous deallocation");
       if (mActor->IPCOpen()) {
         mActor->SendClearTextureHostSync();

gfx/layers/client/TextureClient.h

@@ -426,8 +426,10 @@ public:
    * If the texture flags contain TextureFlags::DEALLOCATE_CLIENT, the destruction
    * will be synchronously coordinated with the compositor side, otherwise it
    * will be done asynchronously.
+   * If sync is true, the destruction will be synchronous regardless of the
+   * texture's flags (bad for performance, use with care).
    */
-  void ForceRemove();
+  void ForceRemove(bool sync = false);
 
   virtual void SetReleaseFenceHandle(FenceHandle aReleaseFenceHandle)
   {