Add a Clock and TickClock interface for mocking out time

media/base/pipeline_unittest.cc

Index: media/base/pipeline_unittest.cc
diff --git a/media/base/pipeline_unittest.cc b/media/base/pipeline_unittest.cc
index a12f91cc35616199a138f41f06bfa12523237be5..32040f8002db7ab1f0776adaecb663359984582f 100644
--- a/media/base/pipeline_unittest.cc
+++ b/media/base/pipeline_unittest.cc
@@ -5,8 +5,10 @@
 #include <vector>
 
 #include "base/bind.h"
+#include "base/clock.h"
 #include "base/message_loop.h"
 #include "base/stl_util.h"
+#include "base/test/simple_test_clock.h"
 #include "base/threading/simple_thread.h"
 #include "media/base/clock.h"
 #include "media/base/gmock_callback_support.h"
@@ -278,6 +280,7 @@ class PipelineTest : public ::testing::Test {
 
   // Fixture members.
   StrictMock<CallbackHelper> callbacks_;
+  base::SimpleTestClock test_clock_;
   MessageLoop message_loop_;
   scoped_refptr<Pipeline> pipeline_;
   scoped_ptr<media::MockFilterCollection> mocks_;
@@ -581,12 +584,6 @@ TEST_F(PipelineTest, EndedCallback) {
   message_loop_.RunUntilIdle();
 }
 
-// Static function & time variable used to simulate changes in wallclock time.
-static int64 g_static_clock_time;
-static base::Time StaticClockFunction() {
-  return base::Time::FromInternalValue(g_static_clock_time);
-}
-
 TEST_F(PipelineTest, AudioStreamShorterThanVideo) {
   base::TimeDelta duration = base::TimeDelta::FromSeconds(10);
 
@@ -598,7 +595,7 @@ TEST_F(PipelineTest, AudioStreamShorterThanVideo) {
 
   // Replace the clock so we can simulate wallclock time advancing w/o using
   // Sleep().
-  pipeline_->SetClockForTesting(new Clock(&StaticClockFunction));
+  pipeline_->SetClockForTesting(new Clock(&test_clock_));
 
   InitializeDemuxer(&streams, duration);
   InitializeAudioRenderer(audio_stream(), false);
@@ -619,8 +616,7 @@ TEST_F(PipelineTest, AudioStreamShorterThanVideo) {
   // Verify that the clock doesn't advance since it hasn't been started by
   // a time update from the audio stream.
   int64 start_time = pipeline_->GetMediaTime().ToInternalValue();
-  g_static_clock_time +=
-      base::TimeDelta::FromMilliseconds(100).ToInternalValue();
+  test_clock_.Advance(base::TimeDelta::FromMilliseconds(100));
   EXPECT_EQ(pipeline_->GetMediaTime().ToInternalValue(), start_time);
 
   // Signal end of audio stream.
@@ -629,8 +625,7 @@ TEST_F(PipelineTest, AudioStreamShorterThanVideo) {
 
   // Verify that the clock advances.
   start_time = pipeline_->GetMediaTime().ToInternalValue();
-  g_static_clock_time +=
-      base::TimeDelta::FromMilliseconds(100).ToInternalValue();
+  test_clock_.Advance(base::TimeDelta::FromMilliseconds(100));
   EXPECT_GT(pipeline_->GetMediaTime().ToInternalValue(), start_time);
 
   // Signal end of video stream and make sure OnEnded() callback occurs.