Move implementation of BrowserList onto an inner, instantiatable class, BrowserListImpl.

chrome/browser/ui/uma_browsing_activity_observer.h

+// Copyright (c) 2012 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_UMA_BROWSING_ACTIVITY_OBSERVER_H_
+#define CHROME_BROWSER_UI_UMA_BROWSING_ACTIVITY_OBSERVER_H_
+
+#include "content/public/browser/notification_registrar.h"
+#include "content/public/browser/notification_observer.h"
+
+namespace chrome {
+
+// This object is instantiated when the first Browser object is added to the
+// list and delete when the last one is removed. It watches for loads and
+// creates histograms of some global object counts.
+class UMABrowsingActivityObserver : public content::NotificationObserver {
+ public:
+  static void Init();
+
+ private:
+  UMABrowsingActivityObserver();
+  virtual ~UMABrowsingActivityObserver();
+
+  // content::NotificationObserver implementation.
+  virtual void Observe(int type,
+                       const content::NotificationSource& source,
+                       const content::NotificationDetails& details) OVERRIDE;
+
+  // Counts the number of active RenderProcessHosts and logs them.
+  void LogRenderProcessHostCount() const;
+
+  // Counts the number of tabs in each browser window and logs them. This is
+  // different than the number of WebContents objects since WebContents objects
+  // can be used for popups and in dialog boxes. We're just counting toplevel
+  // tabs here.
+  void LogBrowserTabCount() const;
+
+  content::NotificationRegistrar registrar_;
+
+  DISALLOW_COPY_AND_ASSIGN(UMABrowsingActivityObserver);
+};
+
+}  // namespace chrome
+
+#endif  // CHROME_BROWSER_UI_UMA_BROWSING_ACTIVITY_OBSERVER_H_