Devtools: Margin resizer in overlay experiment

Source/core/inspector/InspectorOverlay.h

Index: Source/core/inspector/InspectorOverlay.h
diff --git a/Source/core/inspector/InspectorOverlay.h b/Source/core/inspector/InspectorOverlay.h
index bbb18a2e858f084ae7cbba54eeff7739ca052a2a..0b247b018559beaee0de1eda1e235b4618d5987c 100644
--- a/Source/core/inspector/InspectorOverlay.h
+++ b/Source/core/inspector/InspectorOverlay.h
@@ -63,6 +63,13 @@ public:
         virtual void overlaySteppedOver() = 0;
     };
     virtual void setListener(Listener*) = 0;
+
+    class CORE_EXPORT CSSListener : public WillBeGarbageCollectedMixin {
+    public:
+        virtual ~CSSListener() { }
+        virtual void updateCSSProperty(Node* node, long newValue) { }
+    };
+    virtual void setCSSListener(CSSListener*) = 0;
 };
 
 } // namespace blink