cc: Use HighResNow as timebase if it is fast and reliable

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/debug/trace_event.h"
 #include "base/logging.h"
 #include "cc/debug/traced_value.h"
+#include "ui/gfx/frame_time.h"
 
 namespace cc {
 
 Scheduler::Scheduler(SchedulerClient* client,
                      const SchedulerSettings& scheduler_settings)
     : settings_(scheduler_settings),
       client_(client),
       last_set_needs_begin_frame_(false),
       state_machine_(scheduler_settings),
       inside_process_scheduled_actions_(false),
@@ skipping 89 matching lines @@
   ProcessScheduledActions();
 }
 
 base::TimeTicks Scheduler::AnticipatedDrawTime() {
   TRACE_EVENT0("cc", "Scheduler::AnticipatedDrawTime");
 
   if (!last_set_needs_begin_frame_ ||
       last_begin_frame_args_.interval <= base::TimeDelta())
     return base::TimeTicks();
 
-  base::TimeTicks now = base::TimeTicks::Now();
+  base::TimeTicks now = gfx::FrameTime::Now();
   base::TimeTicks timebase = std::max(last_begin_frame_args_.frame_time,
                                       last_begin_frame_args_.deadline);
   int64 intervals = 1 + ((now - timebase) / last_begin_frame_args_.interval);
   return timebase + (last_begin_frame_args_.interval * intervals);
 }
 
 base::TimeTicks Scheduler::LastBeginFrameOnImplThreadTime() {
   return last_begin_frame_args_.frame_time;
 }
 
@@ skipping 196 matching lines @@
 
   if (state_machine_.ShouldTriggerBeginFrameDeadlineEarly())
     PostBeginFrameDeadline(base::TimeTicks());
 }
 
 bool Scheduler::WillDrawIfNeeded() const {
   return !state_machine_.PendingDrawsShouldBeAborted();
 }
 
 }  // namespace cc