Use correct position when setting pos_in_set for tabs.

chrome/browser/ui/views/tabs/tab_strip.cc

 // 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.
 
 #include "chrome/browser/ui/views/tabs/tab_strip.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <iterator>
@@ skipping 1325 matching lines @@
   const int id = incognito ?
       IDR_THEME_TAB_BACKGROUND_INCOGNITO : IDR_THEME_TAB_BACKGROUND;
   *custom_image =
       tp->HasCustomImage(id) || tp->HasCustomImage(IDR_THEME_FRAME) ||
       (incognito && tp->HasCustomImage(IDR_THEME_FRAME_INCOGNITO));
   return id;
 }
 
 void TabStrip::UpdateTabAccessibilityState(const Tab* tab,
                                            ui::AXNodeData* node_data) {
+  if (GetModelIndexOfTab(tab) < 0)

[sky, 2017/03/01 00:31:18]

Assign to local variable to avoid multiple calls.

+    return;
+
   node_data->AddIntAttribute(ui::AX_ATTR_SET_SIZE, tab_count());
-  node_data->AddIntAttribute(ui::AX_ATTR_POS_IN_SET, GetModelIndexOfTab(tab));
+  node_data->AddValidatedIntAttribute(ui::AX_ATTR_INDEX_IN_SET,
+                                      GetModelIndexOfTab(tab));
 }
 
 void TabStrip::MouseMovedOutOfHost() {
   ResizeLayoutTabs();
   if (reset_to_shrink_on_exit_) {
     reset_to_shrink_on_exit_ = false;
     SetStackedLayout(false);
     controller_->StackedLayoutMaybeChanged();
   }
 }
@@ skipping 1423 matching lines @@
           ConvertPointToViewAndGetEventHandler(this, newtab_button_, point);
       if (view)
         return view;
     }
     Tab* tab = FindTabForEvent(point);
     if (tab)
       return ConvertPointToViewAndGetEventHandler(this, tab, point);
   }
   return this;
 }