Adds BeginFrameControl via DevTools.

cc/output/begin_frame_args.h

 // Copyright 2013 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.
 
 #ifndef CC_OUTPUT_BEGIN_FRAME_ARGS_H_
 #define CC_OUTPUT_BEGIN_FRAME_ARGS_H_
 
 #include <memory>
 
 #include "base/location.h"
@@ skipping 64 matching lines @@
   // This is the default interval to use to avoid sprinkling the code with
   // magic numbers.
   static base::TimeDelta DefaultInterval();
 
   bool IsValid() const { return interval >= base::TimeDelta(); }
 
   std::unique_ptr<base::trace_event::ConvertableToTraceFormat> AsValue() const;
   void AsValueInto(base::trace_event::TracedValue* dict) const;
 
   base::TimeTicks frame_time;
-  base::TimeTicks deadline;
+  base::TimeTicks deadline;  // TimeTicks::Max() represents an infinite value.
   base::TimeDelta interval;
   BeginFrameArgsType type;
   bool on_critical_path;
+  bool allow_latency_optimizations;
 
  private:
   BeginFrameArgs(base::TimeTicks frame_time,
                  base::TimeTicks deadline,
                  base::TimeDelta interval,
                  BeginFrameArgsType type);
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_BEGIN_FRAME_ARGS_H_