Reland "Streamline frame detach"

Source/core/frame/FrameHost.cpp

 /*
  * 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 29 matching lines @@
 
 PassOwnPtrWillBeRawPtr<FrameHost> FrameHost::create(Page& page)
 {
     return adoptPtrWillBeNoop(new FrameHost(page));
 }
 
 FrameHost::FrameHost(Page& page)
     : m_page(&page)
     , m_pinchViewport(PinchViewport::create(*this))
     , m_eventHandlerRegistry(adoptPtrWillBeNoop(new EventHandlerRegistry(*this)))
+    , m_subframeCount(0)
 {
 }
 
 // Explicitly in the .cpp to avoid default constructor in .h
 FrameHost::~FrameHost()
 {
 }
 
 Settings& FrameHost::settings() const
 {
@@ skipping 25 matching lines @@
     return *m_eventHandlerRegistry;
 }
 
 void FrameHost::trace(Visitor* visitor)
 {
     visitor->trace(m_page);
     visitor->trace(m_pinchViewport);
     visitor->trace(m_eventHandlerRegistry);
 }
 
+#if ENABLE(ASSERT)
+void checkFrameCountConsistency(int expectedFrameCount, Frame* frame)
+{
+    ASSERT(expectedFrameCount >= 0);
+
+    int actualFrameCount = 0;
+    for (; frame; frame = frame->tree().traverseNext())
+        ++actualFrameCount;
+
+    ASSERT(expectedFrameCount == actualFrameCount);
 }
+#endif
+
+int FrameHost::subframeCount() const
+{
+#if ENABLE(ASSERT)
+    checkFrameCountConsistency(m_subframeCount + 1, m_page->mainFrame());
+#endif
+    return m_subframeCount;
+}
+
+}