Turn ViewportAnchors into stack allocated objects.

Source/web/ResizeViewportAnchor.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ResizeViewportAnchor_h
 #define ResizeViewportAnchor_h
 
 #include "platform/geometry/FloatPoint.h"
 #include "platform/heap/Handle.h"
 #include "web/ViewportAnchor.h"
 
 namespace blink {
 
 class FrameView;
 class PinchViewport;
 
 // The resize anchor saves the current scroll offset of the visual viewport and
 // restores to that scroll offset so that document location appears exactly
 // unchanged to the user.
 class ResizeViewportAnchor : public ViewportAnchor {
+    STACK_ALLOCATED();
 public:
     ResizeViewportAnchor(FrameView& rootFrameView, PinchViewport&);
-    virtual ~ResizeViewportAnchor() { }
-
-    virtual void setAnchor();
-    virtual void restoreToAnchor();
+    ~ResizeViewportAnchor();
 
 private:
     // Inner viewport origin in the reference frame of the root document, in CSS
     // pixels.
     FloatPoint m_pinchViewportInDocument;
 };
 
 } // namespace blink
 
-#endif
+#endif // ResizeViewportAnchor_h