cc: Commit directly to active tree when using single thread.

cc/trees/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/thread_proxy.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/auto_reset.h"
@@ skipping 135 matching lines @@
                  impl_thread_weak_ptr_,
                  &completion));
   completion.Wait();
 }
 
 bool ThreadProxy::IsStarted() const {
   DCHECK(Proxy::IsMainThread());
   return main().started;
 }
 
+bool ThreadProxy::CommitToActiveTree() const {
+  // With ThreadProxy we use a pending tree and activate it once it's ready to
+  // draw.
+  return false;
+}
+
 void ThreadProxy::SetLayerTreeHostClientReady() {
   TRACE_EVENT0("cc", "ThreadProxy::SetLayerTreeHostClientReady");
   Proxy::ImplThreadTaskRunner()->PostTask(
       FROM_HERE,
       base::Bind(&ThreadProxy::SetLayerTreeHostClientReadyOnImplThread,
                  impl_thread_weak_ptr_));
 }
 
 void ThreadProxy::SetLayerTreeHostClientReadyOnImplThread() {
   TRACE_EVENT0("cc", "ThreadProxy::SetLayerTreeHostClientReadyOnImplThread");
@@ skipping 1194 matching lines @@
 }
 
 void ThreadProxy::DidCompletePageScaleAnimationOnImplThread() {
   DCHECK(IsImplThread());
   Proxy::MainThreadTaskRunner()->PostTask(
       FROM_HERE, base::Bind(&ThreadProxy::DidCompletePageScaleAnimation,
                             main_thread_weak_ptr_));
 }
 
 }  // namespace cc