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

chrome/browser/ui/views/frame/browser_view.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_FRAME_BROWSER_VIEW_H_
 #define CHROME_BROWSER_UI_VIEWS_FRAME_BROWSER_VIEW_H_
 
 #include <map>
 #include <memory>
 #include <string>
@@ skipping 359 matching lines @@
           callback) override;
   std::string GetWorkspace() const override;
   bool IsVisibleOnAllWorkspaces() const override;
 
   BookmarkBarView* GetBookmarkBarView() const;
   LocationBarView* GetLocationBarView() const;
   views::View* GetTabContentsContainerView() const;
   ToolbarView* GetToolbarView() const;
 
   // Overridden from TabStripModelObserver:
-  void TabInsertedAt(content::WebContents* contents,
+  void TabInsertedAt(TabStripModel* tab_strip_model,
+                     content::WebContents* contents,
                      int index,
                      bool foreground) override;
   void TabDetachedAt(content::WebContents* contents, int index) override;
   void TabDeactivated(content::WebContents* contents) override;
   void TabStripEmpty() override;
   void WillCloseAllTabs() override;
   void CloseAllTabsCanceled() override;
 
   // Overridden from ui::AcceleratorProvider:
   bool GetAcceleratorForCommandId(int command_id,
@@ skipping 312 matching lines @@
   // The class that registers for keyboard shortcuts for extension commands.
   std::unique_ptr<ExtensionKeybindingRegistryViews>
       extension_keybinding_registry_;
 
   mutable base::WeakPtrFactory<BrowserView> activate_modal_dialog_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserView);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_FRAME_BROWSER_VIEW_H_