ntp: track number of times a user switches pages in a single session

chrome/browser/ui/webui/ntp/new_tab_page_handler.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_NTP_NEW_TAB_PAGE_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_NTP_NEW_TAB_PAGE_HANDLER_H_
 
 #include "base/values.h"
 #include "chrome/common/chrome_notification_types.h"
 #include "content/browser/webui/web_ui.h"
 
 class PrefService;
 class Profile;
 
 // Handler for general New Tab Page functionality that does not belong in a
 // more specialized handler.
 class NewTabPageHandler : public WebUIMessageHandler {
  public:
-  NewTabPageHandler() {}
-  virtual ~NewTabPageHandler() {}
+  NewTabPageHandler();
+  virtual ~NewTabPageHandler();
 
   // WebUIMessageHandler implementation.
   virtual WebUIMessageHandler* Attach(WebUI* web_ui) OVERRIDE;
   virtual void RegisterMessages() OVERRIDE;
 
   // Callback for "closeNotificationPromo".
   void HandleCloseNotificationPromo(const ListValue* args);
 
   // Callback for "notificationPromoViewed".
   void HandleNotificationPromoViewed(const ListValue* args);
@@ skipping 15 matching lines @@
   // Register NTP profile-independent preferences.
   static void RegisterPrefs(PrefService* prefs);
 
   // Registers values (strings etc.) for the page.
   static void GetLocalizedValues(Profile* profile, DictionaryValue* values);
 
   // Permanently dismiss the ntp4 bubble for new users.
   static void DismissIntroMessage(PrefService* prefs);
 
  private:
+  // Tracks the number of times the user has switches pages (for UMA).
+  size_t page_switch_count_;
+
   // The purpose of this enum is to track which page on the NTP is showing.
   // The lower 10 bits of kNTPShownPage are used for the index within the page
   // group, and the rest of the bits are used for the page group ID (defined
   // here).
   static const int kPageIdOffset = 10;
   enum {
     INDEX_MASK = (1 << kPageIdOffset) - 1,
     MOST_VISITED_PAGE_ID = 1 << kPageIdOffset,
     APPS_PAGE_ID = 2 << kPageIdOffset,
     BOOKMARKS_PAGE_ID = 3 << kPageIdOffset,
     LAST_PAGE_ID = BOOKMARKS_PAGE_ID
   };
   static const int kHistogramEnumerationMax =
       (LAST_PAGE_ID >> kPageIdOffset) + 1;
 
   // Helper to send out promo resource change notification.
   void Notify(chrome::NotificationType notification_type);
 
   DISALLOW_COPY_AND_ASSIGN(NewTabPageHandler);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_NTP_NEW_TAB_PAGE_HANDLER_H_