ResourceScheduler should use renderer notifications instead of MRUCache to track renderers.

content/browser/loader/render_view_host_tracker.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 CONTENT_BROWSER_LOADER_RENDER_VIEW_HOST_TRACKER_H_
+#define CONTENT_BROWSER_LOADER_RENDER_VIEW_HOST_TRACKER_H_
+
+#include <set>
+
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
+#include "content/public/browser/render_view_host_observer.h"
+
+namespace content {
+
+// The ResourceDispatcherHost needs to know when renderers are created and
+// destroyed. That happens on the UI thread, but the ResourceDispatcherHost
+// operates on the IO thread. RenderViewHostTracker listens for renderer
+// notifications on the UI thread, then bounces them over to the IO thread so
+// the ResourceDispatcherHost can be notified.
+class CONTENT_EXPORT RenderViewHostTracker : public NotificationObserver {
+ public:
+  RenderViewHostTracker();
+  virtual ~RenderViewHostTracker();
+
+ private:
+  class Observer : public RenderViewHostObserver {
+   public:
+    Observer(RenderViewHost* rvh,
+             RenderViewHostTracker* tracker);
+    virtual ~Observer();
+
+   private:
+    // RenderViewHostObserver interface:
+    virtual void RenderViewHostDestroyed(RenderViewHost* rvh) OVERRIDE;
+
+    RenderViewHostTracker* tracker_;
+  };
+
+  friend class Observer;
+  typedef std::set<Observer*> ObserverSet;
+
+  // NotificationObserver interface:
+  virtual void Observe(int type,
+                       const NotificationSource& source,
+                       const NotificationDetails& details) OVERRIDE;
+
+  void RemoveObserver(Observer* observer);
+
+  content::NotificationRegistrar registrar_;
+  ObserverSet observers_;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_LOADER_RENDER_VIEW_HOST_TRACKER_H_