Fix some grammar in tab_strip_model.cc

chrome/browser/tabs/tab_strip_model.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/tabs/tab_strip_model.h"
 
 #include <algorithm>
 #include <map>
 
 #include "base/command_line.h"
@@ skipping 544 matching lines @@
   DCHECK(ContainsIndex(index));
   if (contents_data_[index]->pinned == pinned)
     return;
 
   if (IsAppTab(index)) {
     if (!pinned) {
       // App tabs should always be pinned.
       NOTREACHED();
       return;
     }
-    // Changing the pinned state of an app tab doesn't effect it's mini-tab
+    // Changing the pinned state of an app tab doesn't affect its mini-tab
     // status.
     contents_data_[index]->pinned = pinned;
   } else {
     // The tab is not an app tab, it's position may have to change as the
     // mini-tab state is changing.
     int non_mini_tab_index = IndexOfFirstNonMiniTab();
     contents_data_[index]->pinned = pinned;
     if (pinned && index != non_mini_tab_index) {
       MoveTabContentsAtImpl(index, non_mini_tab_index, false);
       index = non_mini_tab_index;
@@ skipping 761 matching lines @@
 void TabStripModel::ForgetOpenersAndGroupsReferencing(
     const NavigationController* tab) {
   for (TabContentsDataVector::const_iterator i = contents_data_.begin();
        i != contents_data_.end(); ++i) {
     if ((*i)->group == tab)
       (*i)->group = NULL;
     if ((*i)->opener == tab)
       (*i)->opener = NULL;
   }
 }