Add builders for tracing event's structural arguments

cc/scheduler/scheduler.h

Index: cc/scheduler/scheduler.h
diff --git a/cc/scheduler/scheduler.h b/cc/scheduler/scheduler.h
index 3653c30cb014e0cce4e6d1c253eef9cc0d9c0ff2..afb9e9d0e8e54ec6f689d13ee2c0333b9deeef9c 100644
--- a/cc/scheduler/scheduler.h
+++ b/cc/scheduler/scheduler.h
@@ -20,6 +20,9 @@
 #include "cc/scheduler/scheduler_state_machine.h"
 
 namespace base {
+namespace debug {
+class ConvertableToTraceFormat;
+}
 class SingleThreadTaskRunner;
 }
 
@@ -129,7 +132,7 @@ class CC_EXPORT Scheduler {
   void PollForAnticipatedDrawTriggers();
   void PollToAdvanceCommitState();
 
-  scoped_ptr<base::Value> AsValue() const;
+  scoped_refptr<base::debug::ConvertableToTraceFormat> AsValue() const;
 
   bool IsInsideAction(SchedulerStateMachine::Action action) {
     return inside_action_ == action;
@@ -161,7 +164,7 @@ class CC_EXPORT Scheduler {
     // TimeSourceClient implementation of OnTimerTick triggers a BeginFrame.
     virtual void OnTimerTick() OVERRIDE;
 
-    scoped_ptr<base::Value> AsValue() const;
+    void AsValueInto(base::debug::TracedValue* dict) const;
 
    private:
     BeginFrameArgs CreateSyntheticBeginFrameArgs(base::TimeTicks frame_time);