Add IPC to query capabilities of video input devices.

content/browser/frame_host/render_frame_host_delegate.h

 // Copyright 2013 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_BROWSER_FRAME_HOST_RENDER_FRAME_HOST_DELEGATE_H_
 #define CONTENT_BROWSER_FRAME_HOST_RENDER_FRAME_HOST_DELEGATE_H_
 
 #include <stdint.h>
 
 #include <string>
@@ skipping 137 matching lines @@
   // The render frame has requested access to media devices listed in
   // |request|, and the client should grant or deny that permission by
   // calling |callback|.
   virtual void RequestMediaAccessPermission(
       const MediaStreamRequest& request,
       const MediaResponseCallback& callback);
 
   // Checks if we have permission to access the microphone or camera. Note that
   // this does not query the user. |type| must be MEDIA_DEVICE_AUDIO_CAPTURE
   // or MEDIA_DEVICE_VIDEO_CAPTURE.
   virtual bool CheckMediaAccessPermission(const GURL& security_origin,

[dcheng, 2017/01/20 07:56:50]

It's not introduced by this CL, but please add a TODO and file a bug to use
url::Origin here rather than GURL.

[Guido Urdaneta, 2017/01/20 12:40:58]

Done.

                                           MediaStreamType type);
 
+  // Returns the ID of the default device for the given media device |type|.
+  // If the returned value is an empty string, it means that there is no
+  // default device for the given |type|.
+  virtual std::string GetDefaultMediaDeviceID(MediaStreamType type);
+
   // Get the accessibility mode for the WebContents that owns this frame.
   virtual AccessibilityMode GetAccessibilityMode() const;
 
   // Called when accessibility events or location changes are received
   // from a render frame, when the accessibility mode has the
   // ACCESSIBILITY_MODE_FLAG_WEB_CONTENTS flag set.
   virtual void AccessibilityEventReceived(
       const std::vector<AXEventNotificationDetails>& details) {}
   virtual void AccessibilityLocationChangesReceived(
       const std::vector<AXLocationChangeNotificationDetails>& details) {}
@@ skipping 98 matching lines @@
                                  const gfx::Rect& initial_rect,
                                  bool user_gesture) {}
 
  protected:
   virtual ~RenderFrameHostDelegate() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_RENDER_FRAME_HOST_DELEGATE_H_