Fix Volume slider is captured in screenshot done in touchview mode

chromeos/audio/cras_audio_handler_unittest.cc

Index: chromeos/audio/cras_audio_handler_unittest.cc
diff --git a/chromeos/audio/cras_audio_handler_unittest.cc b/chromeos/audio/cras_audio_handler_unittest.cc
index 7375b4dfa8f0c94e72e3eef31fa6e7789fdfbb4d..d798ad60faf7418828fbc11d5dfcbeb6b516eb8d 100644
--- a/chromeos/audio/cras_audio_handler_unittest.cc
+++ b/chromeos/audio/cras_audio_handler_unittest.cc
@@ -1972,12 +1972,12 @@ TEST_F(CrasAudioHandlerTest, SetOutputVolumePercent) {
   SetUpCrasAudioHandler(audio_nodes);
   EXPECT_EQ(0, test_observer_->output_volume_changed_count());
 
-  cras_audio_handler_->SetOutputVolumePercent(60);
+  const int kVolume = 60;
+  cras_audio_handler_->SetOutputVolumePercent(kVolume);
 
   // Verify the output volume is changed to the designated value,
   // OnOutputNodeVolumeChanged event is fired, and the device volume value
-  // is saved the preferences.
-  const int kVolume = 60;
+  // is saved in the preferences.
   EXPECT_EQ(kVolume, cras_audio_handler_->GetOutputVolumePercent());
   EXPECT_EQ(1, test_observer_->output_volume_changed_count());
   AudioDevice device;
@@ -1986,6 +1986,26 @@ TEST_F(CrasAudioHandlerTest, SetOutputVolumePercent) {
   EXPECT_EQ(kVolume, audio_pref_handler_->GetOutputVolumeValue(&device));
 }
 
+TEST_F(CrasAudioHandlerTest, SetOutputVolumePercentWithoutNotifyingObservers) {
+  AudioNodeList audio_nodes;
+  audio_nodes.push_back(kInternalSpeaker);
+  SetUpCrasAudioHandler(audio_nodes);
+  EXPECT_EQ(0, test_observer_->output_volume_changed_count());
+
+  const int kVolume = 60;
+  cras_audio_handler_->SetOutputVolumePercentWithoutNotifyingObservers(kVolume);
+  // Verify the output volume is changed to the designated value,
+  // OnOutputNodeVolumeChanged event is not fired, and the device volume value
+  // is saved in the preferences.
+  EXPECT_EQ(kVolume, cras_audio_handler_->GetOutputVolumePercent());
+  EXPECT_EQ(0, test_observer_->output_volume_changed_count());
+  AudioDevice device;
+  EXPECT_TRUE(cras_audio_handler_->GetPrimaryActiveOutputDevice(&device));
+  EXPECT_EQ(device.id, kInternalSpeaker.id);
+  EXPECT_EQ(kVolume, audio_pref_handler_->GetOutputVolumeValue(&device));
+  EXPECT_EQ(0, test_observer_->output_volume_changed_count());

[jennyz, 2016/07/29 22:17:14]

This line can be removed. It is the same as line 2001. Nothing changed since
then, so no need to verify output_volume_changed_count() again.

Actually, it might be useful to test a little bit more:
1. Make another SetOutputVolumePercentWithoutNotifyingObservers call to make
sure it works for multiple call case.
2. Make another SetOutputVolumePercent call to make sure the volume change will
be notified. 

[Qiang(Joe) Xu, 2016/08/01 20:28:09]

Done.

+}
+
 TEST_F(CrasAudioHandlerTest, SetOutputVolumeWithDelayedSignal) {
   AudioNodeList audio_nodes;
   audio_nodes.push_back(kInternalSpeaker);