media: Add MediaPermission interface and MediaPermissionDispatcher.

content/renderer/media/media_permission_dispatcher.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 CONTENT_RENDERER_MEDIA_MEDIA_PERMISSION_DISPATCHER_H_
+#define CONTENT_RENDERER_MEDIA_MEDIA_PERMISSION_DISPATCHER_H_
+
+#include <map>
+
+#include "base/threading/thread_checker.h"
+#include "content/common/content_export.h"
+#include "content/common/permission_service.mojom.h"
+#include "content/public/renderer/render_frame_observer.h"
+#include "media/base/media_permission.h"
+
+namespace content {
+
+// MediaPermission implementation in content. This class is not thread safe
+// and should only be used on one thread.
+class CONTENT_EXPORT MediaPermissionDispatcher : public media::MediaPermission,

[xhwang, 2015/01/22 23:40:54]

This file name is following geolocation_dispatcher and
notification_permission_dispatcher.

+                                                 public RenderFrameObserver {
+ public:
+  explicit MediaPermissionDispatcher(RenderFrame* render_frame);
+  ~MediaPermissionDispatcher() override;
+
+  // media::MediaPermission implementation.
+  void HasPermission(Type type,
+                     const GURL& security_origin,

[xhwang, 2015/01/22 23:40:54]

I am using GURL for simplicity. If I use WebSecurityOrigin this class needs to
live in media/blink instead of media/base. Let me know if you have any concerns.

[sandersd (OOO until July 31), 2015/01/24 00:49:22]

I don't know the security implications of choosing one over the other, I
generally support whatever the simplest option is that provides the required
features. (WebSecurityOrigin seems to have a bit of bloat in it.)

[xhwang, 2015/01/26 21:49:06]

Yeah, as discussed offline, I'll keep the current implementation unless there's
a clear better way to enforce security origin check.

+                     const PermissionStatusCB& permission_status_cb) override;
+  void RequestPermission(
+      Type type,
+      const GURL& security_origin,
+      const PermissionStatusCB& permission_status_cb) override;
+
+ private:
+  // Map of request IDs and pending PermissionStatusCBs.
+  typedef std::map<uint32_t, PermissionStatusCB> RequestMap;
+
+  // Callback for |permission_service_| calls.
+  void OnPermissionStatus(uint32_t request_id, PermissionStatus status);
+
+  uint32_t next_request_id_;
+  RequestMap requests_;
+  PermissionServicePtr permission_service_;
+
+  base::ThreadChecker thread_checker_;
+
+  DISALLOW_COPY_AND_ASSIGN(MediaPermissionDispatcher);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_MEDIA_MEDIA_PERMISSION_DISPATCHER_H_