Keep track in the browser of which frames have onunload and onbeforeunload handlers.

chrome/browser/lifetime/browser_close_manager.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/lifetime/browser_close_manager.h"
 
 #include <algorithm>
 #include <iterator>
 #include <vector>
 
@@ skipping 54 matching lines @@
     browser->ResetTryToCloseWindow();
 }
 
 void BrowserCloseManager::TryToCloseBrowsers() {
   // If all browser windows can immediately be closed, fall out of this loop and
   // close the browsers. If any browser window cannot be closed, temporarily
   // stop closing. CallBeforeUnloadHandlers prompts the user and calls
   // OnBrowserReportCloseable with the result. If the user confirms the close,
   // this will trigger TryToCloseBrowsers to try again.
   for (auto* browser : *BrowserList::GetInstance()) {
+    // Set current_browser_ here since if there are no unload handlers, it might
+    // get used synchronously inside TryToCloseWindow.
+    current_browser_ = browser;
     if (browser->TryToCloseWindow(
             false,
             base::Bind(&BrowserCloseManager::OnBrowserReportCloseable, this))) {
-      current_browser_ = browser;
       return;
     }
   }
+  current_browser_ = NULL;
   CheckForDownloadsInProgress();
 }
 
 void BrowserCloseManager::OnBrowserReportCloseable(bool proceed) {
   if (!current_browser_)
     return;
 
   current_browser_ = NULL;
 
   if (proceed)
@@ skipping 88 matching lines @@
       browser->window()->DestroyBrowser();
       // Destroying the browser should have removed it from the browser list.
       DCHECK(BrowserList::GetInstance()->end() ==
              std::find(BrowserList::GetInstance()->begin(),
                        BrowserList::GetInstance()->end(), browser));
     }
   }
 
   g_browser_process->notification_ui_manager()->CancelAll();
 }