Fix scrollbar buttons at hidpi when enable-use-zoom-for-dsf is on.

content/renderer/render_view_impl.h

Index: content/renderer/render_view_impl.h
diff --git a/content/renderer/render_view_impl.h b/content/renderer/render_view_impl.h
index 4c3d165671694994240dae2e0a58f55675ac24a9..e20276175a10ecbdd4f9ea08365fa28ba548892f 100644
--- a/content/renderer/render_view_impl.h
+++ b/content/renderer/render_view_impl.h
@@ -762,13 +762,6 @@ class CONTENT_EXPORT RenderViewImpl
     navigation_gesture_ = gesture;
   }
 
-  // Platform specific theme preferences if any are updated here.
-#if defined(OS_WIN)
-  void UpdateThemePrefs();
-#else
-  void UpdateThemePrefs() {}
-#endif
-
   void UpdateWebViewWithDeviceScaleFactor();
 
   // ---------------------------------------------------------------------------