cc: Add readback and forced draw states to the Scheduler

cc/trees/single_thread_proxy.cc

 // 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.
 
 #include "cc/trees/single_thread_proxy.h"
 
 #include "base/auto_reset.h"
 #include "base/debug/trace_event.h"
 #include "cc/output/context_provider.h"
 #include "cc/output/output_surface.h"
@@ skipping 52 matching lines @@
                           true,  // for_readback
                           &frame))
     return false;
 
   {
     DebugScopedSetImplThread impl(this);
     layer_tree_host_impl_->Readback(pixels, rect);
 
     if (layer_tree_host_impl_->IsContextLost())
       return false;
-
-    layer_tree_host_impl_->SwapBuffers(frame);
   }
-  DidSwapFrame();
 
   return true;
 }
 
 void SingleThreadProxy::FinishAllRendering() {
   DCHECK(Proxy::IsMainThread());
   {
     DebugScopedSetImplThread impl(this);
     layer_tree_host_impl_->FinishAllRendering();
   }
@@ skipping 414 matching lines @@
 void SingleThreadProxy::DidSwapFrame() {
   if (next_frame_is_newly_committed_frame_) {
     next_frame_is_newly_committed_frame_ = false;
     layer_tree_host_->DidCommitAndDrawFrame();
   }
 }
 
 bool SingleThreadProxy::CommitPendingForTesting() { return false; }
 
 }  // namespace cc