Compute snap offsets (both repeat and element based)

Source/core/frame/LocalFrame.h

Index: Source/core/frame/LocalFrame.h
diff --git a/Source/core/frame/LocalFrame.h b/Source/core/frame/LocalFrame.h
index 0b9074b1495c4e0f3ad5946649895e253db202a0..ec97d38e16a0f118dedb5868df4bc48539c7a8a0 100644
--- a/Source/core/frame/LocalFrame.h
+++ b/Source/core/frame/LocalFrame.h
@@ -71,6 +71,7 @@ class LayoutView;
 class TreeScope;
 class ScriptController;
 class SpellChecker;
+class SnapCoordinator;
 class TreeScope;
 template <typename Strategy> class PositionWithAffinityTemplate;
 
@@ -111,6 +112,7 @@ public:
     Element* pagePopupOwner() const { return m_pagePopupOwner.get(); }
 
     LayoutView* contentLayoutObject() const; // Root of the layout tree for the document contained in this frame.
+    SnapCoordinator* snapCoordinator() const;
 
     Editor& editor() const;
     EventHandler& eventHandler() const;
@@ -211,6 +213,8 @@ private:
     const OwnPtrWillBeMember<EventHandler> m_eventHandler;
     const OwnPtrWillBeMember<FrameConsole> m_console;
     const OwnPtrWillBeMember<InputMethodController> m_inputMethodController;
+    OwnPtrWillBeMember<SnapCoordinator> m_snapCoordinator;
+
 
 #if ENABLE(OILPAN)
     // Oilpan: in order to reliably finalize plugin elements with
@@ -309,6 +313,11 @@ inline EventHandler& LocalFrame::eventHandler() const
     return *m_eventHandler;
 }
 
+inline SnapCoordinator* LocalFrame::snapCoordinator() const
+{
+    return m_snapCoordinator.get();
+}
+
 DEFINE_TYPE_CASTS(LocalFrame, Frame, localFrame, localFrame->isLocalFrame(), localFrame.isLocalFrame());
 
 DECLARE_WEAK_IDENTIFIER_MAP(LocalFrame);