Bug 1363347 - Allow multiple external image IDs to be bound to the same image host if owned by the same WRBridge. r=sotaro

gfx/layers/wr/WebRenderBridgeParent.cpp

@@ -661,7 +661,7 @@ WebRenderBridgeParent::RecvRemoveExternalImageId(const ExternalImageId& aImageId
   MOZ_ASSERT(mExternalImageIds.Get(wr::AsUint64(aImageId)).get());
   WebRenderImageHost* wrHost = mExternalImageIds.Get(wr::AsUint64(aImageId)).get();
   if (wrHost) {
-    wrHost->SetWrBridge(nullptr);
+    wrHost->ClearWrBridge();
   }
   mExternalImageIds.Remove(wr::AsUint64(aImageId));
 
@@ -875,7 +875,7 @@ WebRenderBridgeParent::ClearResources()
   }
   DeleteOldImages();
   for (auto iter = mExternalImageIds.Iter(); !iter.Done(); iter.Next()) {
-    iter.Data()->SetWrBridge(nullptr);
+    iter.Data()->ClearWrBridge();
   }
   mExternalImageIds.Clear();
   mCompositableHolder->RemovePipeline(mPipelineId, wr::NewEpoch(mWrEpoch));

gfx/layers/wr/WebRenderImageHost.cpp

@@ -28,6 +28,7 @@ WebRenderImageHost::WebRenderImageHost(const TextureInfo& aTextureInfo)
   : CompositableHost(aTextureInfo)
   , ImageComposite()
   , mWrBridge(nullptr)
+  , mWrBridgeBindings(0)
 {}
 
 WebRenderImageHost::~WebRenderImageHost()
@@ -279,8 +280,25 @@ WebRenderImageHost::GetImageSize() const
 void
 WebRenderImageHost::SetWrBridge(WebRenderBridgeParent* aWrBridge)
 {
-  SetCurrentTextureHost(nullptr);
+  // For image hosts created through ImageBridgeParent, there may be multiple
+  // references to it due to the order of creation and freeing of layers by
+  // the layer tree. However this should be limited to things such as video
+  // which will not be reused across different WebRenderBridgeParent objects.
+  MOZ_ASSERT(aWrBridge);
+  MOZ_ASSERT(!mWrBridge || mWrBridge == aWrBridge);
   mWrBridge = aWrBridge;
+  ++mWrBridgeBindings;
+}
+
+void
+WebRenderImageHost::ClearWrBridge()
+{
+  MOZ_ASSERT(mWrBridgeBindings > 0);
+  --mWrBridgeBindings;
+  if (mWrBridgeBindings == 0) {
+    SetCurrentTextureHost(nullptr);
+    mWrBridge = nullptr;
+  }
 }
 
 } // namespace layers

gfx/layers/wr/WebRenderImageHost.h

@@ -71,6 +71,8 @@ public:
 
   void SetWrBridge(WebRenderBridgeParent* aWrBridge);
 
+  void ClearWrBridge();
+
 protected:
   // ImageComposite
   virtual TimeStamp GetCompositionTime() const override;
@@ -79,6 +81,8 @@ protected:
 
   WebRenderBridgeParent* MOZ_NON_OWNING_REF mWrBridge;
 
+  uint32_t mWrBridgeBindings;
+
   CompositableTextureHostRef mCurrentTextureHost;
 };