Turn ViewportAnchors into stack allocated objects.

Source/web/ViewportAnchor.h

 /*
  * 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 13 matching lines @@
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef ViewportAnchor_h
 #define ViewportAnchor_h
 
+#include "platform/heap/Handle.h"
+
 namespace blink {
 
 class FrameView;
 class PinchViewport;
 
-// Use this class to "anchor" the viewport to a location, perform some operation
-// that may move the viewport around, then restore the viewport to the original
-// location. We support two kinds of anchors, a rotation anchor and a resize
-// anchor.
+// Use derived ViewportAnchor classes to "anchor" the viewport to a location,
+// perform some operation that may move the viewport around, then restore
+// the viewport to the original location.
+// We support two kinds of anchors, a rotation anchor and a resize anchor.
 class ViewportAnchor {
-public:
-    ViewportAnchor(FrameView& rootFrameView, PinchViewport&);
-    virtual ~ViewportAnchor() { }
+    STACK_ALLOCATED();
+protected:
+    ViewportAnchor(FrameView& rootFrameView, PinchViewport& pinchViewport)
+        : m_rootFrameView(&rootFrameView)
+        , m_pinchViewport(&pinchViewport)
+    {
+    }
 
-    virtual void setAnchor() = 0;
-    virtual void restoreToAnchor() = 0;
-
-protected:
-    FrameView& m_rootFrameView;
-    PinchViewport& m_pinchViewport;
+    RawPtrWillBeMember<FrameView> m_rootFrameView;
+    RawPtrWillBeMember<PinchViewport> m_pinchViewport;
 };
 
 } // namespace blink
 
-#endif
+#endif // ViewportAnchor_h