Pipe impl_latency_takes_priority_ to the RenderScheduler.

cc/scheduler/scheduler.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/scheduler/scheduler.h"
 
 #include <algorithm>
 
 #include "base/auto_reset.h"
 #include "base/logging.h"
@@ skipping 335 matching lines @@
 bool Scheduler::OnBeginFrameMixInDelegate(const BeginFrameArgs& args) {
   TRACE_EVENT1("cc,benchmark", "Scheduler::BeginFrame", "args", args.AsValue());
 
   // Trace this begin frame time through the Chrome stack
   TRACE_EVENT_FLOW_BEGIN0(
       TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler.frames"), "BeginFrameArgs",
       args.frame_time.ToInternalValue());
 
   // TODO(brianderson): Adjust deadline in the DisplayScheduler.
   BeginFrameArgs adjusted_args(args);
   adjusted_args.deadline -= EstimatedParentDrawTime();

[Sami, 2015/06/08 11:47:53]

Another option would be to communicate this through the deadline. For example if
your deadline is zero then you won't be on the critical path.

+  adjusted_args.on_critical_path = MainThreadOnCriticalPath();
 
   // Deliver BeginFrames to children.
   // TODO(brianderson): Move this responsibility to the DisplayScheduler.
   if (state_machine_.children_need_begin_frames())
     client_->SendBeginFramesToChildren(adjusted_args);
 
   if (settings_.using_synchronous_renderer_compositor) {
     BeginImplFrameSynchronous(adjusted_args);
     return true;
   }
@@ skipping 453 matching lines @@
 }
 
 bool Scheduler::IsBeginMainFrameSentOrStarted() const {
   return (state_machine_.commit_state() ==
               SchedulerStateMachine::COMMIT_STATE_BEGIN_MAIN_FRAME_SENT ||
           state_machine_.commit_state() ==
               SchedulerStateMachine::COMMIT_STATE_BEGIN_MAIN_FRAME_STARTED);
 }
 
 }  // namespace cc