Refactoring to share MockAudioOutputStream implementations across 3 platforms

chrome/browser/renderer_host/audio_renderer_host_unittest.cc

Index: chrome/browser/renderer_host/audio_renderer_host_unittest.cc
diff --git a/chrome/browser/renderer_host/audio_renderer_host_unittest.cc b/chrome/browser/renderer_host/audio_renderer_host_unittest.cc
index 62be7955aacf7b9e93848020cece56791e65da62..4a3f1035a2d214b77a2f91bd11d584278fff3d6c 100644
--- a/chrome/browser/renderer_host/audio_renderer_host_unittest.cc
+++ b/chrome/browser/renderer_host/audio_renderer_host_unittest.cc
@@ -182,11 +182,6 @@ class AudioRendererHostTest : public testing::Test {
   DISALLOW_COPY_AND_ASSIGN(AudioRendererHostTest);
 };
 
-// Audio output stream only works stably on windows. Also there's no mock
-// audio output streams for mac and linux.
-// TODO(hclam): make these tests work on mac and linux.
-#if defined(OS_WIN)
-
 TEST_F(AudioRendererHostTest, MockStreamDataConversation) {
   scoped_ptr<AudioRendererHost::IPCAudioSource> source(CreateMockStream());
 
@@ -226,4 +221,3 @@ TEST_F(AudioRendererHostTest, MockStreamDataConversation) {
   source->Close();
 }
 
-#endif