Change base::TickClock to a ref counted class.

media/filters/pipeline_integration_test_base.h

Index: media/filters/pipeline_integration_test_base.h
diff --git a/media/filters/pipeline_integration_test_base.h b/media/filters/pipeline_integration_test_base.h
index 2f0d647000a188630e9a82805db024765a7811c4..1847a775a0b1e601896bae7489f63bd793e4c866 100644
--- a/media/filters/pipeline_integration_test_base.h
+++ b/media/filters/pipeline_integration_test_base.h
@@ -38,9 +38,11 @@ extern const char kNullAudioHash[];
 class DummyTickClock : public base::TickClock {
  public:
   DummyTickClock() : now_() {}
-  virtual ~DummyTickClock() {}
   virtual base::TimeTicks NowTicks() override;
+
  private:
+  virtual ~DummyTickClock() {}
+
   base::TimeTicks now_;
 };