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

chrome/browser/ui/views/tabs/browser_tab_strip_controller.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_VIEWS_TABS_BROWSER_TAB_STRIP_CONTROLLER_H_
 #define CHROME_BROWSER_UI_VIEWS_TABS_BROWSER_TAB_STRIP_CONTROLLER_H_
 
 #include <memory>
 
 #include "base/compiler_specific.h"
@@ skipping 60 matching lines @@
   void CreateNewTab() override;
   void CreateNewTabWithLocation(const base::string16& loc) override;
   bool IsIncognito() override;
   void StackedLayoutMaybeChanged() override;
   void OnStartedDraggingTabs() override;
   void OnStoppedDraggingTabs() override;
   void CheckFileSupported(const GURL& url) override;
   SkColor GetToolbarTopSeparatorColor() const override;
 
   // TabStripModelObserver implementation:
-  void TabInsertedAt(content::WebContents* contents,
+  void TabInsertedAt(TabStripModel* tab_strip_model,
+                     content::WebContents* contents,
                      int model_index,
                      bool is_active) override;
   void TabDetachedAt(content::WebContents* contents, int model_index) override;
   void TabSelectionChanged(TabStripModel* tab_strip_model,
                            const ui::ListSelectionModel& old_model) override;
   void TabMoved(content::WebContents* contents,
                 int from_model_index,
                 int to_model_index) override;
   void TabChangedAt(content::WebContents* contents,
                     int model_index,
                     TabChangeType change_type) override;
   void TabReplacedAt(TabStripModel* tab_strip_model,
                      content::WebContents* old_contents,
                      content::WebContents* new_contents,
                      int model_index) override;
-  void TabPinnedStateChanged(content::WebContents* contents,
+  void TabPinnedStateChanged(TabStripModel* tab_strip_model,
+                             content::WebContents* contents,
                              int model_index) override;
   void TabBlockedStateChanged(content::WebContents* contents,
                               int model_index) override;
 
  protected:
   // The context in which SetTabRendererDataFromModel is being called.
   enum TabStatus {
     NEW_TAB,
     EXISTING_TAB
   };
@@ skipping 53 matching lines @@
   std::unique_ptr<ImmersiveRevealedLock> immersive_reveal_lock_;
 
   PrefChangeRegistrar local_pref_registrar_;
 
   base::WeakPtrFactory<BrowserTabStripController> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserTabStripController);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_TABS_BROWSER_TAB_STRIP_CONTROLLER_H_