Add decode() functionality to image elements.

cc/trees/layer_tree_host_impl.h

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_TREES_LAYER_TREE_HOST_IMPL_H_
 #define CC_TREES_LAYER_TREE_HOST_IMPL_H_
 
 #include <stddef.h>
 
 #include <bitset>
@@ skipping 110 matching lines @@
   virtual void DidPrepareTiles() = 0;
 
   // Called when page scale animation has completed on the impl thread.
   virtual void DidCompletePageScaleAnimationOnImplThread() = 0;
 
   // Called when output surface asks for a draw.
   virtual void OnDrawForCompositorFrameSink(
       bool resourceless_software_draw) = 0;
 
   virtual void NeedsImplSideInvalidation() = 0;
+  // Called when a requested image decode completes.
+  virtual void NotifyImageDecodeRequestFinished() = 0;
 
  protected:
   virtual ~LayerTreeHostImplClient() {}
 };
 
 // LayerTreeHostImpl owns the LayerImpl trees as well as associated rendering
 // state.
 class CC_EXPORT LayerTreeHostImpl
     : public InputHandler,
       public TileManagerClient,
@@ skipping 738 matching lines @@
   bool touchpad_and_wheel_scroll_latching_enabled_;
 
   ImplThreadPhase impl_thread_phase_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHostImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_IMPL_H_