Ignore attempts to navigate once a provisional commit has gotten too far along.

Source/core/loader/NavigationScheduler.h

 /*
  * Copyright (C) 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2009 Adam Barth. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
@@ skipping 29 matching lines @@
 #include "wtf/OwnPtr.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 class Document;
 class FormSubmission;
 class LocalFrame;
+class NavigationScheduler;
 class ScheduledNavigation;
 
 class NavigationDisablerForBeforeUnload {
     WTF_MAKE_NONCOPYABLE(NavigationDisablerForBeforeUnload);
-
+    STACK_ALLOCATED();
 public:
     NavigationDisablerForBeforeUnload()
     {
         s_navigationDisableCount++;
     }
     ~NavigationDisablerForBeforeUnload()
     {
         ASSERT(s_navigationDisableCount);
         s_navigationDisableCount--;
     }
     static bool isNavigationAllowed() { return !s_navigationDisableCount; }
 
 private:
     static unsigned s_navigationDisableCount;
 };
 
+class FrameNavigationDisabler {
+    WTF_MAKE_NONCOPYABLE(FrameNavigationDisabler);
+    STACK_ALLOCATED();
+public:
+    explicit FrameNavigationDisabler(LocalFrame*);
+    ~FrameNavigationDisabler();
+
+private:
+    FrameNavigationDisabler() = delete;
+
+    NavigationScheduler& m_navigationScheduler;
+};
+
 class CORE_EXPORT NavigationScheduler final {
     WTF_MAKE_NONCOPYABLE(NavigationScheduler);
     DISALLOW_ALLOCATION();
 public:
     explicit NavigationScheduler(LocalFrame*);
     ~NavigationScheduler();
 
     bool locationChangePending();
 
     void scheduleRedirect(double delay, const String& url);
     void scheduleLocationChange(Document*, const String& url, bool lockBackForwardList = true);
     void schedulePageBlock(Document*);
     void scheduleFormSubmission(Document*, PassRefPtrWillBeRawPtr<FormSubmission>);
     void scheduleReload();
 
     void startTimer();
     void cancel();
 
     DECLARE_TRACE();
 
 private:
+    friend class FrameNavigationDisabler;
+
+    void disableFrameNavigation() { ++m_navigationDisableCount; }
+    void enableFrameNavigation() { --m_navigationDisableCount; }
+    bool isFrameNavigationAllowed() const { return !m_navigationDisableCount; }
+
     bool shouldScheduleReload() const;
     bool shouldScheduleNavigation(const String& url) const;
 
     void timerFired(Timer<NavigationScheduler>*);
     void schedule(PassOwnPtrWillBeRawPtr<ScheduledNavigation>);
 
     static bool mustLockBackForwardList(LocalFrame* targetFrame);
 
     RawPtrWillBeMember<LocalFrame> m_frame;
     Timer<NavigationScheduler> m_timer;
     OwnPtrWillBeMember<ScheduledNavigation> m_redirect;
+    int m_navigationDisableCount;
 };
 
 } // namespace blink
 
 #endif // NavigationScheduler_h