Connecting webrtc-internals WebUI frontend with the backend

chrome/browser/ui/webui/media/webrtc_internals_proxy.h

+// Copyright (c) 2013 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 CHROME_BROWSER_UI_WEBUI_MEDIA_WEBRTC_INTERNALS_PROXY_H_
+#define CHROME_BROWSER_UI_WEBUI_MEDIA_WEBRTC_INTERNALS_PROXY_H_
+
+#include "base/memory/ref_counted.h"
+#include "base/string16.h"
+#include "chrome/browser/media/webrtc_internals_ui_observer.h"
+#include "content/public/browser/browser_thread.h"
+
+class WebRTCInternalsMessageHandler;
+
+// This class is a proxy between WebRTCInternals on the IO thread and
+// WebRTCInternalsMessageHandler on the UI thread.
+// It is ref_counted to ensure that it completes all pending tasks on both
+// threads before destruction.
+class WebRTCInternalsProxy
+    : public media::WebRTCInternalsUIObserver,
+      public base::RefCountedThreadSafe<
+          WebRTCInternalsProxy,
+          content::BrowserThread::DeleteOnUIThread> {
+ public:
+  WebRTCInternalsProxy();
+
+  // WebRTCInternalsUIObserver override.
+  virtual void OnUpdate(const std::string& command,
+                        const base::Value* args) OVERRIDE;
+
+  // Attach a handler and start receiving callbacks from WebRTCInternals.
+  void Attach(WebRTCInternalsMessageHandler* handler);
+
+  // Detach the handler and stop receiving callbacks.
+  void Detach();
+
+ private:
+  friend struct content::BrowserThread::DeleteOnThread<
+      content::BrowserThread::UI>;
+  friend class base::DeleteHelper<WebRTCInternalsProxy>;
+
+  virtual ~WebRTCInternalsProxy();
+
+  void ObserveWebRTCInternalsOnIOThread();
+  void StopObservingWebRTCInternalsOnIOThread();
+  void UpdateOnUIThread(const string16& update);
+
+  WebRTCInternalsMessageHandler* handler_;
+
+  DISALLOW_COPY_AND_ASSIGN(WebRTCInternalsProxy);
+};
+
+#endif  // CHROME_BROWSER_UI_WEBUI_MEDIA_WEBRTC_INTERNALS_PROXY_H_