Maintain minimal error response.

content/browser/renderer_host/render_widget_host_impl.h

Index: content/browser/renderer_host/render_widget_host_impl.h
diff --git a/content/browser/renderer_host/render_widget_host_impl.h b/content/browser/renderer_host/render_widget_host_impl.h
index 490be156247fa26254c9379c526e8022c4e90765..cb3cda83d6d5f22457049b373a4fd9e87ece5b9f 100644
--- a/content/browser/renderer_host/render_widget_host_impl.h
+++ b/content/browser/renderer_host/render_widget_host_impl.h
@@ -138,7 +138,7 @@ class CONTENT_EXPORT RenderWidgetHostImpl
   void CopyFromBackingStore(const gfx::Rect& src_rect,
                             const gfx::Size& accelerated_dst_size,
                             ReadbackRequestCallback& callback,
-                            const SkColorType color_type) override;
+                            const SkColorType preferred_color_type) override;
   bool CanCopyFromBackingStore() override;
 #if defined(OS_ANDROID)
   void LockBackingStore() override;
@@ -163,8 +163,6 @@ class CONTENT_EXPORT RenderWidgetHostImpl
   void RemoveMouseEventCallback(const MouseEventCallback& callback) override;
   void GetWebScreenInfo(blink::WebScreenInfo* result) override;
 
-  SkColorType PreferredReadbackFormat() override;
-
   // Forces redraw in the renderer and when the update reaches the browser
   // grabs snapshot from the compositor. Returns PNG-encoded snapshot.
   void GetSnapshotFromBrowser(