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

content/renderer/media/media_permission_dispatcher_proxy.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.
+
+// A helper class to forward the calls to MediaPermissionDispatcherImpl on UI
+// thread and have the permission status callback on the caller's original
+// non-UI thread.
+
+#ifndef CONTENT_RENDERER_MEDIA_MEDIA_PERMISSION_PROXY_H_
+#define CONTENT_RENDERER_MEDIA_MEDIA_PERMISSION_PROXY_H_
+
+#include "base/memory/weak_ptr.h"
+#include "base/single_thread_task_runner.h"
+#include "content/common/content_export.h"
+#include "content/renderer/media/media_permission_dispatcher.h"
+#include "media/base/media_permission.h"
+
+namespace content {
+
+class CONTENT_EXPORT MediaPermissionDispatcherProxy
+    : public MediaPermissionDispatcher {
+ public:
+  // |ui_task_runner| must be the UI thread. It will be used to call into the
+  // |media_permission| which is the MediaPermissionDispatcherImpl.
+  MediaPermissionDispatcherProxy(
+      scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner,
+      scoped_refptr<base::SingleThreadTaskRunner> caller_task_runner,
+      base::WeakPtr<MediaPermissionDispatcher> media_permission);
+
+  ~MediaPermissionDispatcherProxy() override;
+
+  // MediaPermission implementation.
+  void HasPermission(Type type,
+                     const GURL& security_origin,
+                     const PermissionStatusCB& permission_status_cb) override;
+
+  void RequestPermission(
+      Type type,
+      const GURL& security_origin,
+      const PermissionStatusCB& permission_status_cb) override;
+
+ private:
+  class Core;
+
+  void ReportResult(bool result);
+
+  scoped_ptr<Core> core_;
+
+  base::WeakPtrFactory<MediaPermissionDispatcherProxy> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(MediaPermissionDispatcherProxy);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_MEDIA_MEDIA_PERMISSION_PROXY_H_