Compute minimum repaint and show them in overlay

Source/core/testing/Internals.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013 Apple 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 2011 matching lines @@
         document = toDocument(node);
     } else if (isHTMLIFrameElement(*node)) {
         document = toHTMLIFrameElement(*node).contentDocument();
     } else {
         exceptionState.throwTypeError("The node provided is neither a document nor an IFrame.");
         return;
     }
     document->updateLayoutIgnorePendingStylesheets(Document::RunPostLayoutTasksSynchronously);
 }
 
+void Internals::forceFullRepaint(Document* document, ExceptionState& exceptionState)
+{
+    if (!document || !document->view()) {
+        exceptionState.throwDOMException(InvalidAccessError, document ? "The document's view cannot be retrieved." : "The document provided is invalid.");
+        return;
+    }
+
+    if (RenderView *renderView = document->renderView())
+        renderView->repaintViewAndCompositedLayers();
+}
+
 PassRefPtrWillBeRawPtr<ClientRectList> Internals::draggableRegions(Document* document, ExceptionState& exceptionState)
 {
     return annotatedRegions(document, true, exceptionState);
 }
 
 PassRefPtrWillBeRawPtr<ClientRectList> Internals::nonDraggableRegions(Document* document, ExceptionState& exceptionState)
 {
     return annotatedRegions(document, false, exceptionState);
 }
 
@@ skipping 316 matching lines @@
     } else if (type == "none") {
         webtype = blink::ConnectionTypeNone;
     } else {
         exceptionState.throwDOMException(NotFoundError, ExceptionMessages::failedToEnumerate("connection type", type));
         return;
     }
     networkStateNotifier().setWebConnectionTypeForTest(webtype);
 }
 
 } // namespace WebCore