Reduce calling count of UpdateAppState()

chrome/browser/ui/tabs/tab_strip_model_observer.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_TABS_TAB_STRIP_MODEL_OBSERVER_H_
 #define CHROME_BROWSER_UI_TABS_TAB_STRIP_MODEL_OBSERVER_H_
 
 class TabStripModel;
 
 namespace content {
@@ skipping 22 matching lines @@
 class TabStripModelObserver {
  public:
   // Enumeration of the possible values supplied to TabChangedAt.
   enum TabChangeType {
     // Only the loading state changed.
     LOADING_ONLY,
 
     // Only the title changed and page isn't loading.
     TITLE_NOT_LOADING,
 
-    // Change not characterized by LOADING_ONLY or TITLE_NOT_LOADING.
+    // Only the url changed and loading state isn't changed.
+    URL_CHANGING_ONLY,
+
+    // Change not characterized by LOADING_ONLY, TITLE_NOT_LOADING or
+    // URL_CHANGING_ONLY.
     ALL
   };
 
   enum ChangeReason {
     // Used to indicate that none of the reasons below are responsible for the
     // active tab change.
     CHANGE_REASON_NONE = 0,
     // The active tab changed because the tab's web contents was replaced.
     CHANGE_REASON_REPLACED = 1 << 0,
     // The active tab changed due to a user input event.
@@ skipping 94 matching lines @@
 
   // Sent when the tabstrip model is about to be deleted and any reference held
   // must be dropped.
   virtual void TabStripModelDeleted();
 
  protected:
   virtual ~TabStripModelObserver() {}
 };
 
 #endif  // CHROME_BROWSER_UI_TABS_TAB_STRIP_MODEL_OBSERVER_H_