media: Add MediaPermission interface and MediaPermissionDispatcher.

content/common/permission_service.mojom

 // Copyright 2014 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.
 
 module content;
 
 import "content/public/common/permission_status.mojom";
 
 enum PermissionName {
   GEOLOCATION,
   MIDI_SYSEX,
   NOTIFICATIONS,
+  PROTECTED_MEDIA_IDENTIFIER,
 };
 
 // The Permission service provides permission handling capabilities by exposing
 // methods to check, request, and revoke permissions. It also allows a client to
 // start listening to permission changes.

[ddorwin, 2015/01/26 23:33:46]

How does a client listen to permissions? Is that a missing API or do these
methods not actually match the behaviors described in MediaPermission?

[xhwang, 2015/01/27 00:01:57]

I don't think this file is complete. For example, there's no way to "revoke"
permission. Agreed that this file needs more comments and cleanups. +mlamouri
for comments.

 interface PermissionService {

[ddorwin, 2015/01/26 23:33:46]

Separate CL: It would be nice if this file had detailed comments about user
interaction like you have in media_permission.h.

[xhwang, 2015/01/27 00:01:57]

ditto

   HasPermission(PermissionName permission, string origin)
     => (PermissionStatus status);
   RequestPermission(PermissionName permission, string origin, bool user_gesture)
     => (PermissionStatus status);
 };