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

chrome/browser/ui/fast_unload_controller.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/ui/fast_unload_controller.h"
 
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/single_thread_task_runner.h"
@@ skipping 389 matching lines @@
         tab_needing_before_unload_ack_ = contents;
 
         CoreTabHelper* core_tab_helper =
             CoreTabHelper::FromWebContents(contents);
         core_tab_helper->OnCloseStarted();
 
         // If there's a devtools window attached to |contents|,
         // we would like devtools to call its own beforeunload handlers first,
         // and then call beforeunload handlers for |contents|.
         // See DevToolsWindow::InterceptPageBeforeUnload for details.
-        if (!DevToolsWindow::InterceptPageBeforeUnload(contents))
-          contents->DispatchBeforeUnload();
+        if (!DevToolsWindow::InterceptPageBeforeUnload(contents)) {
+          if (contents->NeedToFireBeforeUnload()) {
+            contents->DispatchBeforeUnload();
+          } else {
+            ProcessPendingTabs(skip_beforeunload);
+          }
+        }
       } else {
         ProcessPendingTabs(skip_beforeunload);
       }
       return;
     }
   }
 
   if (is_calling_before_unload_handlers()) {
     if (!skip_beforeunload)
       on_close_confirmed_.Run(true);
@@ skipping 67 matching lines @@
   }
 }
 
 void FastUnloadController::PostTaskForProcessPendingTabs() {
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE, base::Bind(&FastUnloadController::ProcessPendingTabs,
                             weak_factory_.GetWeakPtr(), false));
 }
 
 }  // namespace chrome