Add a unique frame id and save it on HistoryItem.

Source/core/frame/Frame.h

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999-2001 Lars Knoll <knoll@kde.org>
  *                     1999-2001 Antti Koivisto <koivisto@kde.org>
  *                     2000-2001 Simon Hausmann <hausmann@kde.org>
  *                     2000-2001 Dirk Mueller <mueller@kde.org>
  *                     2000 Stefan Schimanski <1Stein@gmx.de>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
@@ skipping 94 matching lines @@
         InputMethodController& inputMethodController() const;
         FetchContext& fetchContext() const { return loader().fetchContext(); }
         ScriptController& script();
         SpellChecker& spellChecker() const;
 
         RenderView* contentRenderer() const; // Root of the render tree for the document contained in this frame.
         RenderPart* ownerRenderer() const; // Renderer for the element that contains this frame.
 
         void dispatchVisibilityStateChangeEvent();
 
+        int64_t id() const { return m_id; }

[Charlie Reis, 2013/10/29 22:35:03]

It would probably help to document the scope of this ID (e.g., per process or
unique across all processes).

Looks like it's specific to this renderer, so I'm not sure how this fits into
the plans yet.  We already have both a routing ID and a
WebFrame::embedderIdentifier for each frame that are renderer-specific, and this
is a third ID.  Soon we'll have a browser-wide FrameTreeNode ID in the browser
process as well.

Our intention was to eliminate WebFrame::embedderIdentifier in favor of the
routing ID, so that we have two IDs per frame (renderer-specific routing ID and
browser-global FrameTreeNode ID).  Do we need this additional one long term, or
is it a stepping stone?  Can we get rid of WebFrame::embedderIdentifier if we
have this?

+
     // ======== All public functions below this point are candidates to move out of Frame into another class. ========
 
         bool inScope(TreeScope*) const;
 
         // See GraphicsLayerClient.h for accepted flags.
         String layerTreeAsText(unsigned flags = 0) const;
         String trackedRepaintRectsAsText() const;
 
         Settings* settings() const; // can be NULL
 
@@ skipping 55 matching lines @@
         RefPtr<DOMWindow> m_domWindow;
 
         OwnPtr<ScriptController> m_script;
         const OwnPtr<Editor> m_editor;
         const OwnPtr<SpellChecker> m_spellChecker;
         const OwnPtr<FrameSelection> m_selection;
         const OwnPtr<EventHandler> m_eventHandler;
         OwnPtr<AnimationController> m_animationController;
         OwnPtr<InputMethodController> m_inputMethodController;
 
+        int64_t m_id;
+
         float m_pageZoomFactor;
         float m_textZoomFactor;
 
 #if ENABLE(ORIENTATION_EVENTS)
         int m_orientation;
 #endif
 
         bool m_inViewSourceMode;
     };
 
@@ skipping 79 matching lines @@
 
     inline EventHandler& Frame::eventHandler() const
     {
         ASSERT(m_eventHandler);
         return *m_eventHandler;
     }
 
 } // namespace WebCore
 
 #endif // Frame_h