Switching WebRTC browser test from AudioManager::HasAudioOutputDevices() to AudioSystem interface.

content/browser/webrtc/webrtc_content_browsertest_base.h

Index: content/browser/webrtc/webrtc_content_browsertest_base.h
diff --git a/content/browser/webrtc/webrtc_content_browsertest_base.h b/content/browser/webrtc/webrtc_content_browsertest_base.h
index 52f62bfd7f22e824ca3dc15d18e1238a62fca0bb..e6a4228ab6e134d5d948d91f0728521ab5ff242f 100644
--- a/content/browser/webrtc/webrtc_content_browsertest_base.h
+++ b/content/browser/webrtc/webrtc_content_browsertest_base.h
@@ -45,6 +45,9 @@ class WebRtcContentBrowserTestBase : public ContentBrowserTest {
                                        int max_height,
                                        int min_frame_rate,
                                        int max_frame_rate) const;
+
+  // Synchronously checks if the system has audio output devices.
+  static bool HasAudioOutputDevices();
 };
 
 }  // namespace content