cc: modify the waiting condition of forced commit

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 189 matching lines @@
   if (!impl().layer_tree_host_impl) {
     begin_main_frame_sent_completion->Signal();
     request->success = false;
     request->completion.Signal();
     return;
   }
 
   impl().readback_request = request;
 
   impl().scheduler->SetNeedsForcedCommitForReadback();
-  if (impl().scheduler->CommitPending()) {
+  if (impl().scheduler->IsBeginMainFrameSent()) {
     begin_main_frame_sent_completion->Signal();
     return;
   }
 
   impl().begin_main_frame_sent_completion_event =
       begin_main_frame_sent_completion;
 }
 
 void ThreadProxy::FinishAllRendering() {
   DCHECK(Proxy::IsMainThread());
@@ skipping 1514 matching lines @@
 
   impl().timing_history.DidActivatePendingTree();
 }
 
 void ThreadProxy::DidManageTiles() {
   DCHECK(IsImplThread());
   impl().scheduler->DidManageTiles();
 }
 
 }  // namespace cc