Add metrics to keep track of the tab activate/deactivate cycle

chrome/browser/ui/ash/launcher/browser_status_monitor.cc

 // Copyright 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.
 
 #include "chrome/browser/ui/ash/launcher/browser_status_monitor.h"
 
 #include "ash/aura/wm_window_aura.h"
 #include "ash/common/shelf/shelf_item_types.h"
 #include "ash/common/wm_window_property.h"
 #include "ash/resources/grit/ash_resources.h"
@@ skipping 238 matching lines @@
     state = ChromeLauncherController::APP_STATE_WINDOW_ACTIVE;
   UpdateAppItemState(new_contents, state);
   UpdateBrowserItemState();
 
   if (tab_strip_model->GetActiveWebContents() == new_contents)
     SetShelfIDForBrowserWindowContents(browser, new_contents);
 
   AddWebContentsObserver(new_contents);
 }
 
-void BrowserStatusMonitor::TabInsertedAt(content::WebContents* contents,
+void BrowserStatusMonitor::TabInsertedAt(TabStripModel* tab_strip_model,
+                                         content::WebContents* contents,
                                          int index,
                                          bool foreground) {
   // An inserted tab is not active - ActiveTabChanged() will be called to
   // activate. We initialize therefore with |APP_STATE_INACTIVE|.
   UpdateAppItemState(contents,
                      ChromeLauncherController::APP_STATE_INACTIVE);
   AddWebContentsObserver(contents);
 }
 
 void BrowserStatusMonitor::TabClosingAt(TabStripModel* tab_strip_mode,
@@ skipping 55 matching lines @@
     content::WebContents* contents) {
   return launcher_controller_->GetShelfIDForWebContents(contents);
 }
 
 void BrowserStatusMonitor::SetShelfIDForBrowserWindowContents(
     Browser* browser,
     content::WebContents* web_contents) {
   launcher_controller_->GetBrowserShortcutLauncherItemController()->
       SetShelfIDForBrowserWindowContents(browser, web_contents);
 }