Reland "Streamline frame detach"

Source/core/frame/FrameHost.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 67 matching lines @@
     PinchViewport& pinchViewport() const;
     EventHandlerRegistry& eventHandlerRegistry() const;
 
     const AtomicString& overrideEncoding() const { return m_overrideEncoding; }
     void setOverrideEncoding(const AtomicString& encoding) { m_overrideEncoding = encoding; }
 
     ConsoleMessageStorage& consoleMessageStorage() const;
 
     void trace(Visitor*);
 
+    // Don't allow more than a certain number of frames in a page.
+    // This seems like a reasonable upper bound, and otherwise mutually
+    // recursive frameset pages can quickly bring the program to its knees
+    // with exponential growth in the number of frames.
+    static const int maxNumberOfFrames = 1000;
+    void incrementSubframeCount() { ++m_subframeCount; }
+    void decrementSubframeCount() { ASSERT(m_subframeCount); --m_subframeCount; }
+    int subframeCount() const;
+
 private:
     explicit FrameHost(Page&);
 
     RawPtrWillBeMember<Page> m_page;
     const OwnPtrWillBeMember<PinchViewport> m_pinchViewport;
     const OwnPtrWillBeMember<EventHandlerRegistry> m_eventHandlerRegistry;
     const OwnPtrWillBeMember<ConsoleMessageStorage> m_consoleMessageStorage;
 
     AtomicString m_overrideEncoding;
+    int m_subframeCount;
 };
 
 }
 
 #endif // FrameHost_h