Implement aura::Window::CreateCompositorFrameSink()

cc/output/compositor_frame_sink.h

 // Copyright 2012 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_OUTPUT_COMPOSITOR_FRAME_SINK_H_
 #define CC_OUTPUT_COMPOSITOR_FRAME_SINK_H_
 
 #include <deque>
 #include <memory>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/threading/thread_checker.h"
 #include "cc/cc_export.h"
 #include "cc/output/context_provider.h"
 #include "cc/output/overlay_candidate_validator.h"
 #include "cc/output/vulkan_context_provider.h"
 #include "cc/resources/returned_resource.h"
+#include "cc/surfaces/surface_id.h"
 #include "gpu/command_buffer/common/texture_in_use_response.h"
 #include "ui/gfx/color_space.h"
 
 namespace gpu {
 class GpuMemoryBufferManager;
 }
 
 namespace cc {
 
 class CompositorFrame;
@@ skipping 85 matching lines @@
   //
   // CompositorFrameSink::Invalidate is called by the compositor to notify that
   // there's new content.
   virtual void Invalidate() {}
 
   // For successful swaps, the implementation must call
   // DidReceiveCompositorFrameAck() asynchronously when the frame has been
   // processed in order to unthrottle the next frame.
   virtual void SubmitCompositorFrame(CompositorFrame frame) = 0;
 
+  // Notify that the surface is no longer in use (and is okay to be evicted) so
+  // that its resources gets returned in time.
+  virtual void EvictFrame() {}

[Fady Samuel, 2017/05/08 18:17:35]

We prefer pure virtual in cc.

[Peng, 2017/05/08 20:14:00]

Tried it and found out making it pure will modify a lot of subclasses which are
only for testing. And right now, this class only has one pure virtual method.
Probably it is better to keep EvictFrame() non-pure.

+
  protected:
   // Bound to the ContextProvider to hear about when it is lost and inform the
   // |client_|.
   void DidLoseCompositorFrameSink();
 
   CompositorFrameSinkClient* client_ = nullptr;
 
   struct CompositorFrameSink::Capabilities capabilities_;
   scoped_refptr<ContextProvider> context_provider_;
   scoped_refptr<ContextProvider> worker_context_provider_;
   scoped_refptr<VulkanContextProvider> vulkan_context_provider_;
   gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager_;
   SharedBitmapManager* shared_bitmap_manager_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(CompositorFrameSink);
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_COMPOSITOR_FRAME_SINK_H_