Cleanup various WebView/WebFrame APIs to properly handle remote frames.

Source/core/page/Page.h

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 110 matching lines @@
 
     ViewportDescription viewportDescription() const;
 
     static void refreshPlugins(bool reload);
     PluginData* pluginData() const;
 
     EditorClient& editorClient() const { return *m_editorClient; }
     SpellCheckerClient& spellCheckerClient() const { return *m_spellCheckerClient; }
     UndoStack& undoStack() const { return *m_undoStack; }
 
-    void setMainFrame(PassRefPtr<Frame>);
-    Frame* mainFrame() const { return m_mainFrame.get(); }
+    void setMainFrame(Frame*);
+    Frame* mainFrame() const { return m_mainFrame; }
     // Escape hatch for existing code that assumes that the root frame is
     // always a LocalFrame. With OOPI, this is not always the case. Code that
     // depends on this will generally have to be rewritten to propagate any
     // necessary state through all renderer processes for that page and/or
     // coordinate/rely on the browser process to help dispatch/coordinate work.
-    LocalFrame* deprecatedLocalMainFrame() const { return toLocalFrame(m_mainFrame.get()); }
+    LocalFrame* deprecatedLocalMainFrame() const { return toLocalFrame(m_mainFrame); }
 
     void documentDetached(Document*);
 
     bool openedByDOM() const;
     void setOpenedByDOM();
 
     void incrementSubframeCount() { ++m_subframeCount; }
     void decrementSubframeCount() { ASSERT(m_subframeCount); --m_subframeCount; }
     int subframeCount() const { checkSubframeCountConsistency(); return m_subframeCount; }
 
@@ skipping 103 matching lines @@
     const OwnPtr<Chrome> m_chrome;
     const OwnPtrWillBeMember<DragCaretController> m_dragCaretController;
     const OwnPtrWillBeMember<DragController> m_dragController;
     const OwnPtr<FocusController> m_focusController;
     const OwnPtrWillBeMember<ContextMenuController> m_contextMenuController;
     const OwnPtr<InspectorController> m_inspectorController;
     const OwnPtrWillBeMember<PointerLockController> m_pointerLockController;
     OwnPtr<ScrollingCoordinator> m_scrollingCoordinator;
     const OwnPtrWillBeMember<UndoStack> m_undoStack;
 
-    RefPtr<Frame> m_mainFrame;
+    // Typically, the main frame and Page should both be owned by the embedder,
+    // which must call Page::willBeDestroyed() prior to destroying Page. This
+    // call detaches the main frame and clears this pointer, thus ensuring that
+    // this field only references a live main frame.
+    //
+    // However, there are several locations (InspectorOverlay, SVGImage, and
+    // WebPagePopupImpl) which don't hold a reference to the main frame at all
+    // after creating it. These are still safe because they always create a
+    // Frame with a FrameView. FrameView and Frame hold references to each
+    // other, thus keeping each other alive. The call to willBeDestroyed()
+    // breaks this cycle, so the frame is still properly destroyed once no
+    // longer needed.
+    Frame* m_mainFrame;
 
     mutable RefPtr<PluginData> m_pluginData;
 
     BackForwardClient* m_backForwardClient;
     EditorClient* const m_editorClient;
     SpellCheckerClient* const m_spellCheckerClient;
     StorageClient* m_storageClient;
     OwnPtrWillBeMember<ValidationMessageClient> m_validationMessageClient;
 
     UseCounter m_useCounter;
@@ skipping 21 matching lines @@
     WillBeHeapHashSet<RawPtrWillBeWeakMember<MultisamplingChangedObserver> > m_multisamplingChangedObservers;
 
     // A pointer to all the interfaces provided to in-process Frames for this Page.
     // FIXME: Most of the members of Page should move onto FrameHost.
     OwnPtrWillBeMember<FrameHost> m_frameHost;
 };
 
 } // namespace WebCore
 
 #endif // Page_h