Implement aura::Window::CreateCompositorFrameSink()

cc/output/compositor_frame_sink.h

Index: cc/output/compositor_frame_sink.h
diff --git a/cc/output/compositor_frame_sink.h b/cc/output/compositor_frame_sink.h
index f8b7a47b4e6c97fc06934a4a4062377f270e1e45..296a5877d6e511317b4923cc6639de93c2ca50ff 100644
--- a/cc/output/compositor_frame_sink.h
+++ b/cc/output/compositor_frame_sink.h
@@ -16,6 +16,7 @@
 #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"
 
@@ -121,6 +122,10 @@ class CC_EXPORT CompositorFrameSink {
   // 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_|.