Maintain minimal error response.

content/browser/frame_host/render_widget_host_view_child_frame.h

Index: content/browser/frame_host/render_widget_host_view_child_frame.h
diff --git a/content/browser/frame_host/render_widget_host_view_child_frame.h b/content/browser/frame_host/render_widget_host_view_child_frame.h
index 7e55f0a9d4c6e34b66d0cfc199d5c127d641b1ce..9954ab6ddd7f6f382f185227b7863109abc8b9f5 100644
--- a/content/browser/frame_host/render_widget_host_view_child_frame.h
+++ b/content/browser/frame_host/render_widget_host_view_child_frame.h
@@ -80,10 +80,11 @@ class CONTENT_EXPORT RenderWidgetHostViewChildFrame
                         const gfx::Range& range) override;
   void SelectionBoundsChanged(
       const ViewHostMsg_SelectionBounds_Params& params) override;
-  void CopyFromCompositingSurface(const gfx::Rect& src_subrect,
-                                  const gfx::Size& dst_size,
-                                  ReadbackRequestCallback& callback,
-                                  const SkColorType color_type) override;
+  void CopyFromCompositingSurface(
+      const gfx::Rect& src_subrect,
+      const gfx::Size& dst_size,
+      ReadbackRequestCallback& callback,
+      const SkColorType preferred_color_type) override;
   void CopyFromCompositingSurfaceToVideoFrame(
       const gfx::Rect& src_subrect,
       const scoped_refptr<media::VideoFrame>& target,
@@ -132,8 +133,6 @@ class CONTENT_EXPORT RenderWidgetHostViewChildFrame
   BrowserAccessibilityManager* CreateBrowserAccessibilityManager(
       BrowserAccessibilityDelegate* delegate) override;
 
-  SkColorType PreferredReadbackFormat() override;
-
  protected:
   friend class RenderWidgetHostView;