cc: Add main frame timing info to frame timing tracker.

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 673 matching lines @@
 
   if (!impl().layer_tree_host_impl->settings().impl_side_painting) {
     DCHECK_GT(impl().layer_tree_host_impl->memory_allocation_limit_bytes(), 0u);
   }
   begin_main_frame_state->memory_allocation_limit_bytes =
       impl().layer_tree_host_impl->memory_allocation_limit_bytes();
   begin_main_frame_state->memory_allocation_priority_cutoff =
       impl().layer_tree_host_impl->memory_allocation_priority_cutoff();
   begin_main_frame_state->evicted_ui_resources =
       impl().layer_tree_host_impl->EvictedUIResourcesExist();
+  impl().layer_tree_host_impl->SetBeginMainFrameTime(
+      impl().scheduler->LastBeginImplFrameTime());

[enne (OOO), 2015/03/06 21:27:55]

I still think this is a little weird, in that a lost context on a previous frame
will make the next frame look long, even if that content hadn't even requested a
begin main frame / needs commit.

If the goal is "time to get content on screen", then maybe it makes sense to
time from SetNeedsCommit on the main thread instead?

Sorry for all the confusion here.  I still feel like maybe I'm just missing
something.

   Proxy::MainThreadTaskRunner()->PostTask(
       FROM_HERE,
       base::Bind(&ThreadProxy::BeginMainFrame,
                  main_thread_weak_ptr_,
                  base::Passed(&begin_main_frame_state)));
   devtools_instrumentation::DidRequestMainThreadFrame(
       impl().layer_tree_host_id);
   impl().timing_history.DidBeginMainFrame();
 }
 
@@ skipping 683 matching lines @@
   impl().scheduler->DidPrepareTiles();
 }
 
 void ThreadProxy::DidCompletePageScaleAnimationOnImplThread() {
   DCHECK(IsImplThread());
   Proxy::MainThreadTaskRunner()->PostTask(
       FROM_HERE, base::Bind(&ThreadProxy::DidCompletePageScaleAnimation,
                             main_thread_weak_ptr_));
 }
 
+base::TimeTicks ThreadProxy::GetNextBeginImplFrameTimeIfRequested() const {
+  DCHECK(IsImplThread());
+  return impl().scheduler->NextBeginImplFrameTimeIfRequested();
+}
+
 }  // namespace cc