cc: Send all begin frames using a PostTask.

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 417ee26fd078bedd0512ff845c0d3d2ce53fe4ab..14432ed4396e70963d22844095a834889d644124 100644
--- a/cc/scheduler/delay_based_time_source.h
+++ b/cc/scheduler/delay_based_time_source.h
@@ -12,6 +12,7 @@
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/weak_ptr.h"
+#include "base/time/tick_clock.h"
 #include "base/values.h"
 #include "cc/base/cc_export.h"
 
@@ -31,13 +32,13 @@ class CC_EXPORT DelayBasedTimeSourceClient {
   virtual ~DelayBasedTimeSourceClient() {}
 };
 
-// This timer implements a time source that achieves the specified interval
-// in face of millisecond-precision delayed callbacks and random queueing
-// delays. DelayBasedTimeSource uses base::TimeTicks::Now as its timebase.
+// Simple timer that keeps track of its last and next tick times can an use an
+// optional clock for timing.
 class CC_EXPORT DelayBasedTimeSource {
  public:
-  explicit DelayBasedTimeSource(base::SingleThreadTaskRunner* task_runner);
-  virtual ~DelayBasedTimeSource();
+  DelayBasedTimeSource(base::SingleThreadTaskRunner* task_runner,
+                       base::TickClock* clock);
+  ~DelayBasedTimeSource();
 
   void SetClient(DelayBasedTimeSourceClient* client);
 
@@ -54,12 +55,7 @@ class CC_EXPORT DelayBasedTimeSource {
   base::TimeTicks LastTickTime() const;
   base::TimeTicks NextTickTime() const;
 
-  virtual void AsValueInto(base::trace_event::TracedValue* dict) const;
-
- protected:
-  // Virtual for testing.
-  virtual base::TimeTicks Now() const;
-  virtual std::string TypeString() const;
+  void AsValueInto(base::trace_event::TracedValue* dict) const;
 
  private:
   void PostNextTickTask(base::TimeTicks now);
@@ -67,6 +63,10 @@ class CC_EXPORT DelayBasedTimeSource {
 
   void OnTimerTick();
 
+  base::TimeTicks Now();

[brianderson, 2016/07/13 21:14:49]

Should this just go away now that there's a tick clock?

+
+  base::SingleThreadTaskRunner* task_runner_;
+  base::TickClock* clock_;
   DelayBasedTimeSourceClient* client_;
 
   bool active_;
@@ -78,9 +78,6 @@ class CC_EXPORT DelayBasedTimeSource {
   base::TimeTicks next_tick_time_;
 
   base::CancelableClosure tick_closure_;
-
-  base::SingleThreadTaskRunner* task_runner_;
-
   base::WeakPtrFactory<DelayBasedTimeSource> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DelayBasedTimeSource);