Do the murdering.

content/child/webthemeengine_impl_mac.h

Index: content/child/webthemeengine_impl_mac.h
diff --git a/content/child/webthemeengine_impl_mac.h b/content/child/webthemeengine_impl_mac.h
index 7f7a69159483d9dbe087b25f267c80256d6ee525..3fb0cd1fb47a7d9e7b25bbc56ade71e59176c7c0 100644
--- a/content/child/webthemeengine_impl_mac.h
+++ b/content/child/webthemeengine_impl_mac.h
@@ -11,13 +11,6 @@ namespace content {
 
 class WebThemeEngineImpl : public blink::WebThemeEngine {
  public:
-  // blink::WebThemeEngine implementation.
-  virtual void paintScrollbarThumb(
-      blink::WebCanvas* canvas,
-      blink::WebThemeEngine::State part,
-      blink::WebThemeEngine::Size state,
-      const blink::WebRect& rect,
-      const blink::WebThemeEngine::ScrollbarInfo& extra_params);
 };
 
 }  // namespace content