Declare a new name for CompositingSurface completion callback.

content/browser/frame_host/render_widget_host_view_guest.cc

Index: content/browser/frame_host/render_widget_host_view_guest.cc
diff --git a/content/browser/frame_host/render_widget_host_view_guest.cc b/content/browser/frame_host/render_widget_host_view_guest.cc
index 4b7b62640953ccaadd9d044b03966e87e95b46f2..fef98d9796d26218a0ddb124492629c8ece6141e 100644
--- a/content/browser/frame_host/render_widget_host_view_guest.cc
+++ b/content/browser/frame_host/render_widget_host_view_guest.cc
@@ -370,7 +370,7 @@ void RenderWidgetHostViewGuest::SelectionBoundsChanged(
 void RenderWidgetHostViewGuest::CopyFromCompositingSurface(
     const gfx::Rect& src_subrect,
     const gfx::Size& dst_size,
-    const base::Callback<void(bool, const SkBitmap&)>& callback,
+    CompletionCallback& callback,
     const SkColorType color_type) {
   CHECK(guest_);
   guest_->CopyFromCompositingSurface(src_subrect, dst_size, callback);