Refactor the Get*Hardware* routines a bit.

content/test/webrtc_audio_device_test.cc

Index: content/test/webrtc_audio_device_test.cc
===================================================================
--- content/test/webrtc_audio_device_test.cc	(revision 110480)
+++ content/test/webrtc_audio_device_test.cc	(working copy)
@@ -19,6 +19,7 @@
 #include "content/common/view_messages.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/common/content_paths.h"
+#include "content/renderer/media/audio_device.h"
 #include "content/renderer/media/webrtc_audio_device_impl.h"
 #include "content/renderer/render_process.h"
 #include "content/renderer/render_thread_impl.h"
@@ -130,12 +131,20 @@
       base::Bind(&SetupTask::UninitializeIOThread, new SetupTask(this)));
   WaitForIOThreadCompletion();
   mock_process_.reset();
+  SetAudioUtilCallback(NULL);
 }
 
 bool WebRTCAudioDeviceTest::Send(IPC::Message* message) {
   return channel_->Send(message);
 }
 
+void WebRTCAudioDeviceTest::SetAudioUtilCallback(AudioUtilInterface* callback) {
+  // Invalidate any potentially cached values since the new callback should
+  // be used for those queries.
+  AudioHardware::ResetCache();
+  audio_util_callback_ = callback;
+}
+
 void WebRTCAudioDeviceTest::InitializeIOThread(const char* thread_name) {
   // We initialize COM (STA) on our IO thread as is done in Chrome.
   // See BrowserProcessSubThread::Init.