Refactor media permission dispatcher class and create proxy class for non-UI threads.

content/renderer/media/media_permission_dispatcher_impl.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.
+
+// MediaPermission implementation which dispatches queries/requests to Mojo
+// PermissionService. It relies on its base class MediaPermissionDispatcher to
+// manage pending callbacks. Non-UI threads could create
+// MediaPermissionDispatcherProxy by calling CreateProxy such that calls will be
+// executed on the UI thread which is where this object lives.
+
+#ifndef CONTENT_RENDERER_MEDIA_MEDIA_PERMISSION_DISPATCHER_IMPL_H_
+#define CONTENT_RENDERER_MEDIA_MEDIA_PERMISSION_DISPATCHER_IMPL_H_
+
+#include <map>
+
+#include "base/single_thread_task_runner.h"
+#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 "content/renderer/media/media_permission_dispatcher.h"
+#include "media/base/media_permission.h"
+
+namespace content {
+
+class CONTENT_EXPORT MediaPermissionDispatcherImpl
+    : public MediaPermissionDispatcher,
+      public RenderFrameObserver {
+ public:
+  explicit MediaPermissionDispatcherImpl(RenderFrame* render_frame);
+  ~MediaPermissionDispatcherImpl() override;
+
+  // media::MediaPermission implementation.
+  void HasPermission(Type type,
+                     const GURL& security_origin,
+                     const PermissionStatusCB& permission_status_cb) override;
+
+  // MediaStreamDevicePermissionContext doesn't support RequestPermission yet
+  // and will always return CONTENT_SETTING_BLOCK.
+  void RequestPermission(
+      Type type,
+      const GURL& security_origin,
+      const PermissionStatusCB& permission_status_cb) override;
+
+  // Create MediaPermissionDispatcherProxy object which will dispatch the
+  // callback between the |caller_task_runner| and |task_runner_| in a thread
+  // safe way. This can be called from non-UI thread.
+  scoped_ptr<media::MediaPermission> CreateProxy(
+      scoped_refptr<base::SingleThreadTaskRunner> caller_task_runner);
+
+ private:
+  // Callback for |permission_service_| calls.
+  void OnPermissionStatus(uint32_t request_id, PermissionStatus status);
+
+  const scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+
+  PermissionServicePtr permission_service_;
+
+  base::WeakPtrFactory<MediaPermissionDispatcherImpl> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(MediaPermissionDispatcherImpl);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_MEDIA_MEDIA_PERMISSION_DISPATCHER_IMPL_H_