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

chrome/browser/ui/fast_unload_controller.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/fast_unload_controller.h"
 
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/single_thread_task_runner.h"
@@ skipping 270 matching lines @@
   DCHECK_EQ(content::NOTIFICATION_WEB_CONTENTS_DISCONNECTED, type);
 
   registrar_.Remove(this, content::NOTIFICATION_WEB_CONTENTS_DISCONNECTED,
                     source);
   ClearUnloadState(content::Source<content::WebContents>(source).ptr());
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // FastUnloadController, TabStripModelObserver implementation:
 
-void FastUnloadController::TabInsertedAt(content::WebContents* contents,
+void FastUnloadController::TabInsertedAt(TabStripModel* tab_strip_model,
+                                         content::WebContents* contents,
                                          int index,
                                          bool foreground) {
   TabAttachedImpl(contents);
 }
 
 void FastUnloadController::TabDetachedAt(content::WebContents* contents,
                                          int index) {
   TabDetachedImpl(contents);
 }
 
@@ skipping 170 matching lines @@
   }
 }
 
 void FastUnloadController::PostTaskForProcessPendingTabs() {
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE, base::Bind(&FastUnloadController::ProcessPendingTabs,
                             weak_factory_.GetWeakPtr()));
 }
 
 }  // namespace chrome