Enable new getUserMedia audio constraints algorithm behind a flag.

content/renderer/media/user_media_client_impl.h

Index: content/renderer/media/user_media_client_impl.h
diff --git a/content/renderer/media/user_media_client_impl.h b/content/renderer/media/user_media_client_impl.h
index 0e4f587aef068442872418923581d8887bebd493..b7e92eb79f03546368403c542f3d612987cf3713 100644
--- a/content/renderer/media/user_media_client_impl.h
+++ b/content/renderer/media/user_media_client_impl.h
@@ -37,10 +37,11 @@ class TaskRunner;
 }
 
 namespace content {
-class PeerConnectionDependencyFactory;
+class AudioCaptureSettings;
 class MediaStreamAudioSource;
 class MediaStreamDispatcher;
 class MediaStreamVideoSource;
+class PeerConnectionDependencyFactory;
 class VideoCaptureSettings;
 
 // UserMediaClientImpl is a delegate for the Media Stream GetUserMedia API.
@@ -121,10 +122,13 @@ class CONTENT_EXPORT UserMediaClientImpl
 
   // Returns no value if there is no request being processed. Use only for
   // testing.
-  // TODO(guidou): Remove this method once spec-compliant constraints algorithm
-  // for audio is implemented. http://crbug.com/543997
+  // TODO(guidou): Remove this function. http://crbug.com/706408
   base::Optional<bool> AutomaticOutputDeviceSelectionEnabledForCurrentRequest();
 
+  // Intended to be used only for testing.
+  const AudioCaptureSettings& AudioCaptureSettingsForCurrentRequest() const;

[miu, 2017/06/19 21:18:44]

Couple suggestions:

1. naming/style: Test-only methods should have the "XXXForTesting()" naming
pattern. This allows presubmit scripts to warn developers when future code
changes are made.

2. These methods both just call into |current_request_info_|. So, perhaps it'd
be simpler to just provide one accessor here for that:

  UserMediaRequestInfo* current_request_info_for_testing() const {
    return current_request_info_.get();
  }

...and then the helper you have in the test code would:

  auto* const request_info =
user_media_client->current_request_info_for_testing();
  ASSERT_TRUE(request_info);
  return request_info->audio_settings();

[Guido Urdaneta, 2017/06/20 12:18:48]

Did not expose |current_request_info_| because its type is internal to
user_media_client_impl.cc. I see little value in making that type public just
for a unit test.
Instead renamed the methods to XXXForTesting() as per your suggestion #1.

+  const VideoCaptureSettings& VideoCaptureSettingsForCurrentRequest() const;
+
  private:
   class UserMediaRequestInfo;
   typedef std::vector<blink::WebMediaStreamSource> LocalStreamSources;
@@ -225,21 +229,25 @@ class CONTENT_EXPORT UserMediaClientImpl
 
   const ::mojom::MediaDevicesDispatcherHostPtr& GetMediaDevicesDispatcher();
 
-  void SelectAudioInputDevice(
+  // TODO(guidou): Remove these functions. http://crbug.com/706408
+  void LegacySetupAudioInput();
+  void LegacySelectAudioInputDevice(
       const blink::WebUserMediaRequest& user_media_request,
       const EnumerationResult& device_enumeration);
 
-  void SetupVideoInput(const blink::WebUserMediaRequest& user_media_request);
+  void SetupAudioInput(const blink::WebUserMediaRequest& user_media_request);
+  void SelectAudioSettings(const blink::WebUserMediaRequest& user_media_request,
+                           std::vector<::mojom::AudioInputDeviceCapabilitiesPtr>
+                               audio_input_capabilities);
 
+  void SetupVideoInput(const blink::WebUserMediaRequest& user_media_request);
   void SelectVideoDeviceSettings(
       const blink::WebUserMediaRequest& user_media_request,
       std::vector<::mojom::VideoInputDeviceCapabilitiesPtr>
           video_input_capabilities);
-
   void FinalizeSelectVideoDeviceSettings(
       const blink::WebUserMediaRequest& user_media_request,
       const VideoCaptureSettings& settings);
-
   void FinalizeSelectVideoContentSettings(
       const blink::WebUserMediaRequest& user_media_request,
       const VideoCaptureSettings& settings);