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

content/renderer/media/media_permission_dispatcher_proxy.h

Index: content/renderer/media/media_permission_dispatcher_proxy.h
diff --git a/content/renderer/media/media_permission_dispatcher_proxy.h b/content/renderer/media/media_permission_dispatcher_proxy.h
new file mode 100644
index 0000000000000000000000000000000000000000..bd3e9e18196d2f5f3a612738481ba1241683696b
--- /dev/null
+++ b/content/renderer/media/media_permission_dispatcher_proxy.h
@@ -0,0 +1,54 @@
+// 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,

[perkj_chrome, 2015/09/22 08:24:16]

protected:

[guoweis_left_chromium, 2015/09/22 18:48:49]

I'm not sure I understand this comment. They are public in the base class. Why
do we want to move them into protected?

[perkj_chrome, 2015/09/23 13:25:23]

This is up to you. But my thinging was that a user of this class uses this
through the MediaPermission interface and not the
MediaPermissionDispatcherProxy. As you say, it does not really matter since they
are public in the beginning so in practice they are public. 

I asked two colleagues, one voted they should public as you say since they are
public in the base class and one voted they should be private... I could not
find anything in the style guide so I would leave them as public....

+                     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_;
+
+  DISALLOW_COPY_AND_ASSIGN(MediaPermissionDispatcherProxy);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_MEDIA_MEDIA_PERMISSION_PROXY_H_