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

content/public/browser/web_contents_media_capture_id.h

 // Copyright 2016 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 CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_MEDIA_CAPTURE_ID_H_
 #define CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_MEDIA_CAPTURE_ID_H_
 
 #include <string>
 
 #include "content/common/content_export.h"
 #include "ipc/ipc_message.h"
 
 namespace content {
 
 struct CONTENT_EXPORT WebContentsMediaCaptureId {
  public:
   WebContentsMediaCaptureId() = default;
   WebContentsMediaCaptureId(int render_process_id, int main_render_frame_id)
       : render_process_id(render_process_id),
         main_render_frame_id(main_render_frame_id) {}
 
   WebContentsMediaCaptureId(int render_process_id,
                             int main_render_frame_id,
-                            bool enable_auto_throttling)
+                            bool enable_auto_throttling,
+                            bool mute_source)
       : render_process_id(render_process_id),
         main_render_frame_id(main_render_frame_id),
-        enable_auto_throttling(enable_auto_throttling) {}
+        enable_auto_throttling(enable_auto_throttling),
+        mute_source(mute_source) {}
 
   bool operator<(const WebContentsMediaCaptureId& other) const;
   bool operator==(const WebContentsMediaCaptureId& other) const;
 
   // Return true if render_process_id or main_render_frame_id is invalid.
   bool is_null() const;
 
   std::string ToString() const;
 
   // Tab video and audio capture need render process id and render frame id.
   int render_process_id = MSG_ROUTING_NONE;
   int main_render_frame_id = MSG_ROUTING_NONE;
 
   bool enable_auto_throttling = false;
+  bool mute_source = false;
 
   // Create WebContentsMediaCaptureId based on a string.
   static WebContentsMediaCaptureId Parse(const std::string& str);
 
   // Check whether the device id indicates that this is a web contents stream.
   static bool IsWebContentsDeviceId(const std::string& device_id);
 
   // Function to extract the target render frame id's from a media stream
   // request's device id.
   static bool ExtractTabCaptureTarget(const std::string& device_id,
                                       int* render_process_id,
                                       int* main_render_frame_id);
 
-  // Parses the media stream request |device_id| and returns true if both 1) the
-  // format is valid, and 2) the throttling option is set to auto.
-  static bool IsAutoThrottlingOptionSet(const std::string& device_id);
+  // Parses the media stream request |device_id| and returns true if the
+  // format is valid. |*auto_throttling| will be stored whether the |device_id|
+  // indicated auto throttling. |*mute_source| will stored whether |device_id|
+  // requests us to mute the source audio during sharing.
+  // The caller can pass nullptr for either |auto_throttling| or |mute_source|,
+  // if the value is uninteresting.
+  static bool ExtractOptions(const std::string& device_id,

[miu, 2016/09/07 21:10:03]

Looking at the calls to this function, only one of the two bool* is ever
provided. This suggests you should either: 1) Keep the
IsAutoThrottlingOptionSet() function and add a new IsMuteSourceOptionSet()
function; or 2) Delete the IsAudioThrottlingOptionSet() function and make all
callers just use Parse() and then read the bool field they are interested in
from the WebContentsMediaCaptureId struct.

I'll leave it up to you which you think fits cleanest. ;)

[qiangchen, 2016/09/09 23:32:08]

Done.

+                             bool* auto_throttling,
+                             bool* mute_source);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_MEDIA_CAPTURE_ID_H_