Add GetPreferredFormats method to media::VideoCapturerSource.

media/capture/video_capturer_source.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_CAPTURE_VIDEO_CAPTURER_SOURCE_H_
 #define MEDIA_CAPTURE_VIDEO_CAPTURER_SOURCE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 37 matching lines @@
   using VideoCaptureDeviceFormatsCB =
       base::Callback<void(const media::VideoCaptureFormats&)>;
 
   using RunningCallback = base::Callback<void(bool)>;
 
   // Collects the formats that can currently be used.
   // |max_requested_height|, |max_requested_width|, and
   // |max_requested_frame_rate| is used by Tab and Screen capture to decide what
   // resolution/framerate to generate. |callback| is triggered when the formats
   // have been collected.
+  // TODO(guidou): Remove this method. http://crbug.com/706408
   virtual void GetCurrentSupportedFormats(

[miu, 2017/04/05 20:58:36]

Does this still need to be a virtual method (are there overrides in subclasses)?

[Guido Urdaneta, 2017/04/05 21:14:59]

Yes, LocalVideoCapturerSource (defined in user_media_client_impl.cc) still has
an implementation of it, but we will remove the method in a future iteration
when we retire the old constraints algorithm.

       int max_requested_width,
       int max_requested_height,
       double max_requested_frame_rate,
-      const VideoCaptureDeviceFormatsCB& callback) = 0;
+      const VideoCaptureDeviceFormatsCB& callback);
+
+  // Returns formats that are preferred and can currently be used. May be empty
+  // if no formats are available or known.
+  virtual VideoCaptureFormats GetPreferredFormats() = 0;
 
   // Starts capturing frames using the capture |params|. |new_frame_callback| is
   // triggered when a new video frame is available.
   // If capturing is started successfully then |running_callback| will be
   // called with a parameter of true. Note that some implementations may
   // simply reject StartCapture (by calling running_callback with a false
   // argument) if called with the wrong task runner.
   // If capturing fails to start or stopped due to an external event then
   // |running_callback| will be called with a parameter of false.
   // |running_callback| will always be called on the same thread as the
@@ skipping 39 matching lines @@
   // Stops capturing frames and clears all callbacks including the
   // SupportedFormatsCallback callback. Note that queued frame callbacks
   // may still occur after this call, so the caller must take care to
   // use refcounted or weak references in |new_frame_callback|.
   virtual void StopCapture() = 0;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_CAPTURE_VIDEO_CAPTURER_SOURCE_H_