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

chrome/browser/ui/toolbar/toolbar_actions_bar.h

 // Copyright 2014 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_TOOLBAR_TOOLBAR_ACTIONS_BAR_H_
 #define CHROME_BROWSER_UI_TOOLBAR_TOOLBAR_ACTIONS_BAR_H_
 
 #include <stddef.h>
 
 #include <memory>
@@ skipping 256 matching lines @@
   void OnToolbarActionAdded(const ToolbarActionsModel::ToolbarItem& item,
                             int index) override;
   void OnToolbarActionRemoved(const std::string& action_id) override;
   void OnToolbarActionMoved(const std::string& action_id, int index) override;
   void OnToolbarActionUpdated(const std::string& action_id) override;
   void OnToolbarVisibleCountChanged() override;
   void OnToolbarHighlightModeChanged(bool is_highlighting) override;
   void OnToolbarModelInitialized() override;
 
   // TabStripModelObserver:
-  void TabInsertedAt(content::WebContents* contents,
+  void TabInsertedAt(TabStripModel* tab_strip_model,
+                     content::WebContents* contents,
                      int index,
                      bool foreground) override;
 
   // Resizes the delegate (if necessary) to the preferred size using the given
   // |tween_type| and optionally suppressing the chevron.
   void ResizeDelegate(gfx::Tween::Type tween_type, bool suppress_chevron);
 
   // Returns the action for the given |id|, if one exists.
   ToolbarActionViewController* GetActionForId(const std::string& action_id);
 
@@ skipping 77 matching lines @@
   ScopedObserver<TabStripModel, TabStripModelObserver> tab_strip_observer_;
 
   base::ObserverList<ToolbarActionsBarObserver> observers_;
 
   base::WeakPtrFactory<ToolbarActionsBar> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ToolbarActionsBar);
 };
 
 #endif  // CHROME_BROWSER_UI_TOOLBAR_TOOLBAR_ACTIONS_BAR_H_