Remove GpuHostMsg_FrameDrawn and replace with client channel swap ack

cc/output/output_surface.cc

 // Copyright (c) 2013 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.
 
 #include "cc/output/output_surface.h"
 
 #include <algorithm>
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 205 matching lines @@
 gfx::Size OutputSurface::SurfaceSize() const {
   return surface_size_;
 }
 
 void OutputSurface::BindFramebuffer() {
   DCHECK(context_provider_.get());
   context_provider_->ContextGL()->BindFramebuffer(GL_FRAMEBUFFER, 0);
 }
 
 void OutputSurface::SwapBuffers(CompositorFrame* frame) {
+  // TODO(sievers): Make OutputSurface::SwapBuffers() pure virtual.
+  // The implementation here is used for tests only.
   if (frame->software_frame_data) {
     PostSwapBuffersComplete();
     client_->DidSwapBuffers();
     return;
   }
 
   DCHECK(context_provider_.get());
   DCHECK(frame->gl_frame_data);
 
   if (frame->gl_frame_data->sub_buffer_rect ==
@@ skipping 30 matching lines @@
   TRACE_EVENT1("cc", "OutputSurface::SetMemoryPolicy",
                "bytes_limit_when_visible", policy.bytes_limit_when_visible);
   // Just ignore the memory manager when it says to set the limit to zero
   // bytes. This will happen when the memory manager thinks that the renderer
   // is not visible (which the renderer knows better).
   if (policy.bytes_limit_when_visible)
     client_->SetMemoryPolicy(policy);
 }
 
 }  // namespace cc