Fix the segfault on Linux when closing a tab that is in tab fullscreen mode.

chrome/browser/ui/browser.cc

 // Copyright (c) 2011 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/browser.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #include <shellapi.h>
 #endif  // OS_WIN
@@ skipping 3183 matching lines @@
   registrar_.Add(this, content::NOTIFICATION_TAB_CONTENTS_DISCONNECTED,
                  content::Source<TabContents>(contents->tab_contents()));
 
   registrar_.Add(this, content::NOTIFICATION_INTERSTITIAL_ATTACHED,
                  content::Source<TabContents>(contents->tab_contents()));
 }
 
 void Browser::TabClosingAt(TabStripModel* tab_strip_model,
                            TabContentsWrapper* contents,
                            int index) {
+  if (fullscreened_tab_ == contents) {
+    ExitTabbedFullscreenModeIfNecessary();
+    // The call to exit fullscreen may result in asynchronous notification of
+    // fullscreen state change (e.g., on Linux). We don't want to rely on it
+    // to call NotifyTabOfFullscreenExitIfNecessary(), because at that point
+    // |fullscreen_tab_| may not be valid. Instead, we call it here to clean up
+    // tab fullscreen related state.
+    NotifyTabOfFullscreenExitIfNecessary();
+  }
   content::NotificationService::current()->Notify(
       content::NOTIFICATION_TAB_CLOSING,
       content::Source<NavigationController>(&contents->controller()),
       content::NotificationService::NoDetails());
 
   // Sever the TabContents' connection back to us.
   SetAsDelegate(contents, NULL);
 }
 
 void Browser::TabDetachedAt(TabContentsWrapper* contents, int index) {
@@ skipping 2285 matching lines @@
 }
 
 void Browser::UpdateFullscreenExitBubbleContent() {
   GURL url;
   if (fullscreened_tab_)
     url = fullscreened_tab_->tab_contents()->GetURL();
 
   window_->UpdateFullscreenExitBubbleContent(
       url, GetFullscreenExitBubbleType());
 }