Let Contraints Controll Mute/Unmute Audio Local Playback For Desktop Sharing

content/public/common/media_stream_request.h

Index: content/public/common/media_stream_request.h
diff --git a/content/public/common/media_stream_request.h b/content/public/common/media_stream_request.h
index 55171ab9489b3ffccaf6121e32799514e34985a0..b18de54e25328c2aa9f19d0428f096972a316683 100644
--- a/content/public/common/media_stream_request.h
+++ b/content/public/common/media_stream_request.h
@@ -204,17 +204,17 @@ typedef std::map<MediaStreamType, MediaStreamDevices> MediaStreamDeviceMap;
 // Tab-only stuff and Pepper-only stuff being passed around to all clients,
 // which is icky.
 struct CONTENT_EXPORT MediaStreamRequest {
-  MediaStreamRequest(
-      int render_process_id,
-      int render_frame_id,
-      int page_request_id,
-      const GURL& security_origin,
-      bool user_gesture,
-      MediaStreamRequestType request_type,
-      const std::string& requested_audio_device_id,
-      const std::string& requested_video_device_id,
-      MediaStreamType audio_type,
-      MediaStreamType video_type);
+  MediaStreamRequest(int render_process_id,
+                     int render_frame_id,
+                     int page_request_id,
+                     const GURL& security_origin,
+                     bool user_gesture,
+                     MediaStreamRequestType request_type,
+                     const std::string& requested_audio_device_id,
+                     const std::string& requested_video_device_id,
+                     MediaStreamType audio_type,
+                     MediaStreamType video_type,
+                     bool disable_local_echo);
 
   MediaStreamRequest(const MediaStreamRequest& other);
 
@@ -256,6 +256,10 @@ struct CONTENT_EXPORT MediaStreamRequest {
   // Flag to indicate if the request contains video.
   MediaStreamType video_type;
 
+  // Flag for desktop share to indicate whether to mute the source audio during

[miu, 2016/09/16 21:22:48]

nit: s/desktop share/Desktop or WebContents capture/

and

s/mute the source audio/prevent playing the captured audio locally/

(note: "WebContents" may sound slightly weird, but "tab" is not a concept in
src/content code)

[qiangchen, 2016/09/16 22:02:24]

Done.

+  // sharing.
+  bool disable_local_echo;
+
   // True if all ancestors of the requesting frame have the same origin.
   bool all_ancestors_have_same_origin;
 };