Make MediaInternalsUI talk to MediaInternals.

chrome/browser/ui/webui/media_internals_proxy.h

+// Copyright (c) 2011 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_INTERNALS_PROXY_H_
+#define CHROME_BROWSER_UI_WEBUI_MEDIA_INTERNALS_PROXY_H_
+#pragma once
+
+#include "base/memory/ref_counted.h"
+#include "base/string16.h"
+#include "chrome/browser/media/media_internals_observer.h"
+
+class IOThread;
+class MediaInternalsUI;
+
+// This class is a proxy between MediaInternals (on the IO thread) and
+// MediaInternalsUI (on the UI thread).
+// It is ref_counted to ensure that it completes all pending Tasks on both
+// threads before destruction.
+class MediaInternalsProxy

[Evan Stade, 2011/06/29 20:13:01]

seems this class should be a WebUIMessageHandler (see *_handler.{h,cc})

[Scott Franklin, 2011/06/29 23:47:08]

As far as I can see, all of those still have proxies.

In fact, net_internals_ui appears to do exactly the same thing. They just name
it IOThreadImpl instead of calling it a proxy.

[Evan Stade, 2011/06/30 22:24:27]

Most chrome:// pages have handlers but not dedicated proxies (most of them don't
directly deal with multi-threading, instead they use UI-thread APIs for
accessing data). If you want/need separate proxy and handler classes, that's
fine with me.

+    : public MediaInternalsObserver,
+      public base::RefCountedThreadSafe<MediaInternalsProxy> {
+ public:
+  MediaInternalsProxy();
+
+  // Methods for MediaInternalsUI. Called on the UI thread.
+  // Register a UI to receive callbacks from MediaInternals.
+  void AttachUI(MediaInternalsUI* ui);

[scherkus (not reviewing), 2011/06/29 18:49:32]

pedantic nit: space out these methods w/ one blank line so it isn't a WALLOFTEXT

[Scott Franklin, 2011/06/29 23:47:08]

Done.

+  // Unregister the same.
+  void DetachUI();
+  // Have MediaInternals send all the data it has.
+  void GetEverything();
+
+  // MediaInternalsObserver implementation. Called on the IO thread.
+  virtual void OnUpdate(const string16& update);
+
+ private:
+  friend class base::RefCountedThreadSafe<MediaInternalsProxy>;
+  virtual ~MediaInternalsProxy();
+
+  void ObserveMediaInternalsOnIOThread();
+  void StopObservingMediaInternalsOnIOThread();
+  void GetEverythingOnIOThread();
+  void UpdateUIOnUIThread(const string16& update);
+
+  MediaInternalsUI* ui_;
+  IOThread* io_thread_;
+
+  DISALLOW_COPY_AND_ASSIGN(MediaInternalsProxy);
+};
+
+#endif  // CHROME_BROWSER_UI_WEBUI_MEDIA_INTERNALS_PROXY_H_