Devtools [LayoutEditor]: show selector info and highlight affected nodes

Source/core/inspector/InspectorOverlayHost.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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 34 matching lines @@
     }
     ~InspectorOverlayHost();
     DECLARE_TRACE();
 
     void resume();
     void stepOver();
     void startPropertyChange(const String&);
     void changeProperty(float delta);
     void endPropertyChange();
     void clearSelection(bool commitChanges);
+    void nextSelector();
+    void previousSelector();
+    String currentSelectorInfo();
 
     class Listener : public WillBeGarbageCollectedMixin {
     public:
         virtual ~Listener() { }
         virtual void overlayResumed() = 0;
         virtual void overlaySteppedOver() = 0;
         virtual void overlayStartedPropertyChange(const String&) = 0;
         virtual void overlayPropertyChanged(float cssDelta) = 0;
         virtual void overlayEndedPropertyChange() = 0;
         virtual void overlayClearSelection(bool commitChanges) = 0;
+        virtual void overlayNextSelector() = 0;
+        virtual void overlayPreviousSelector() = 0;
+        virtual String overlayCurrentSelectorInfo() = 0;
     };
     void setListener(Listener* listener) { m_listener = listener; }
 
 private:
     InspectorOverlayHost();
 
     RawPtrWillBeMember<Listener> m_listener;
 
 };
 
 } // namespace blink
 
 #endif // InspectorOverlayHost_h