Move histograms and supporting code that don't belong in content out.

chrome/browser/ui/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/ui/tabs/tab_strip_model.h"
 
 #include <algorithm>
 #include <map>
 #include <string>
 
@@ skipping 1097 matching lines @@
 
   // We now return to our regularly scheduled shutdown procedure.
   bool retval = true;
   while (close_tracker.HasNext()) {
     WebContents* closing_contents = close_tracker.Next();
     int index = GetIndexOfWebContents(closing_contents);
     // Make sure we still contain the tab.
     if (index == kNoTab)
       continue;
 
-    closing_contents->OnCloseStarted();
+    CoreTabHelper* core_tab_helper =
+        CoreTabHelper::FromWebContents(closing_contents);
+    core_tab_helper->OnCloseStarted();
 
     // Update the explicitly closed state. If the unload handlers cancel the
     // close the state is reset in Browser. We don't update the explicitly
     // closed state if already marked as explicitly closed as unload handlers
     // call back to this if the close is allowed.
     if (!closing_contents->GetClosedByUserGesture()) {
       closing_contents->SetClosedByUserGesture(
           close_types & CLOSE_USER_GESTURE);
     }
 
@@ skipping 154 matching lines @@
 void TabStripModel::ForgetOpenersAndGroupsReferencing(
     const WebContents* tab) {
   for (WebContentsDataVector::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;
   }
 }