Refactoring the way begin frame sources inside scheduler work.

cc/scheduler/delay_based_time_source.h

Index: cc/scheduler/delay_based_time_source.h
diff --git a/cc/scheduler/delay_based_time_source.h b/cc/scheduler/delay_based_time_source.h
index 9faaeac4651d873f18fdc12a64cc4d1dc95d12d0..a5ea2fb129f251764ea27c3bbc5dc08d54f1ed80 100644
--- a/cc/scheduler/delay_based_time_source.h
+++ b/cc/scheduler/delay_based_time_source.h
@@ -5,7 +5,10 @@
 #ifndef CC_SCHEDULER_DELAY_BASED_TIME_SOURCE_H_
 #define CC_SCHEDULER_DELAY_BASED_TIME_SOURCE_H_
 
+#include <string>
+
 #include "base/memory/weak_ptr.h"
+#include "base/values.h"
 #include "cc/base/cc_export.h"
 #include "cc/scheduler/time_source.h"
 
@@ -32,17 +35,21 @@ class CC_EXPORT DelayBasedTimeSource : public TimeSource {
 
   // Get the last and next tick times. NextTickTime() returns null when
   // inactive.
-  virtual base::TimeTicks LastTickTime() OVERRIDE;
-  virtual base::TimeTicks NextTickTime() OVERRIDE;
+  virtual base::TimeTicks LastTickTime() const OVERRIDE;
+  virtual base::TimeTicks NextTickTime() const OVERRIDE;
 
   // Virtual for testing.
   virtual base::TimeTicks Now() const;
 
+  virtual scoped_ptr<base::Value> AsValue() const;
+
  protected:
   DelayBasedTimeSource(base::TimeDelta interval,
                        base::SingleThreadTaskRunner* task_runner);
   virtual ~DelayBasedTimeSource();
 
+  virtual std::string TypeString() const;
+
   base::TimeTicks NextTickTarget(base::TimeTicks now);
   void PostNextTickTask(base::TimeTicks now);
   void OnTimerFired();
@@ -86,6 +93,8 @@ class DelayBasedTimeSourceHighRes : public DelayBasedTimeSource {
                               base::SingleThreadTaskRunner* task_runner);
   virtual ~DelayBasedTimeSourceHighRes();
 
+  virtual std::string TypeString() const OVERRIDE;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(DelayBasedTimeSourceHighRes);
 };