Bug 1429694 - Fix WebRenderLayerManager::ClearCachedResources r=nical

gfx/layers/wr/WebRenderBridgeChild.cpp

@@ -599,6 +599,10 @@ void
 WebRenderBridgeChild::BeginClearCachedResources()
 {
   mIsInClearCachedResources = true;
+  // Clear display list and animtaions at parent side before clearing cached
+  // resources on client side. It prevents to clear resources before clearing
+  // display list at parent side.
+  SendClearCachedResources();
 }
 
 void
@@ -609,7 +613,6 @@ WebRenderBridgeChild::EndClearCachedResources()
     return;
   }
   ProcessWebRenderParentCommands();
-  SendClearCachedResources();
   mIsInClearCachedResources = false;
 }
 

gfx/layers/wr/WebRenderLayerManager.cpp

@@ -514,6 +514,7 @@ void
 WebRenderLayerManager::ClearCachedResources(Layer* aSubtree)
 {
   WrBridge()->BeginClearCachedResources();
+  mWebRenderCommandBuilder.ClearCachedResources();
   DiscardImages();
   WrBridge()->EndClearCachedResources();
 }

gfx/layers/wr/WebRenderUserData.cpp

@@ -88,6 +88,10 @@ WebRenderImageData::ClearCachedResources()
     WrBridge()->RemovePipelineIdForCompositable(mPipelineId.ref());
     mPipelineId.reset();
   }
+
+  if (mImageClient) {
+    mImageClient = nullptr;
+  }
 }
 
 Maybe<wr::ImageKey>