Mac HiDPI: Fix scale factor on external display

content/browser/renderer_host/render_widget_host_view_mac.h

Index: content/browser/renderer_host/render_widget_host_view_mac.h
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.h b/content/browser/renderer_host/render_widget_host_view_mac.h
index 31cc6d6ec439e0880f5c8565e0665221fed6be27..4c61a847c15d9a55c4d1e14da14bac2eaa25b84c 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.h
+++ b/content/browser/renderer_host/render_widget_host_view_mac.h
@@ -135,6 +135,9 @@ class RenderWidgetHostViewMacEditCommandHelper;
 
   // recursive globalFrameDidChange protection:
   BOOL handlingGlobalFrameDidChange_;
+
+  // The scale factor of the display this view is in.
+  float deviceScaleFactor_;
 }
 
 @property(nonatomic, readonly) NSRange selectedRange;