Pass task runners to AudioManager constructor.

media/audio/alsa/alsa_output_unittest.cc

Index: media/audio/alsa/alsa_output_unittest.cc
diff --git a/media/audio/alsa/alsa_output_unittest.cc b/media/audio/alsa/alsa_output_unittest.cc
index 1b1386347f9437c21865c9fa64b71936090ee735..a93e0a5732365619a0f27a8de3860158d14ae8b5 100644
--- a/media/audio/alsa/alsa_output_unittest.cc
+++ b/media/audio/alsa/alsa_output_unittest.cc
@@ -6,6 +6,7 @@
 
 #include "base/macros.h"
 #include "base/strings/stringprintf.h"
+#include "base/thread_task_runner_handle.h"
 #include "media/audio/alsa/alsa_output.h"
 #include "media/audio/alsa/alsa_wrapper.h"
 #include "media/audio/alsa/audio_manager_alsa.h"
@@ -72,7 +73,10 @@ class MockAlsaWrapper : public AlsaWrapper {
 
 class MockAudioManagerAlsa : public AudioManagerAlsa {
  public:
-  MockAudioManagerAlsa() : AudioManagerAlsa(&fake_audio_log_factory_) {}
+  MockAudioManagerAlsa()
+      : AudioManagerAlsa(base::ThreadTaskRunnerHandle::Get(),
+                         base::ThreadTaskRunnerHandle::Get(),
+                         &fake_audio_log_factory_) {}
   MOCK_METHOD0(Init, void());
   MOCK_METHOD0(HasAudioOutputDevices, bool());
   MOCK_METHOD0(HasAudioInputDevices, bool());
@@ -93,12 +97,6 @@ class MockAudioManagerAlsa : public AudioManagerAlsa {
     delete stream;
   }
 
-  // We don't mock this method since all tests will do the same thing
-  // and use the current task runner.
-  scoped_refptr<base::SingleThreadTaskRunner> GetTaskRunner() override {
-    return base::MessageLoop::current()->task_runner();
-  }
-
  private:
   FakeAudioLogFactory fake_audio_log_factory_;
 };