ash: Clean up system background layer.

ui/aura/remote_root_window_host_win.cc

Index: ui/aura/remote_root_window_host_win.cc
diff --git a/ui/aura/remote_root_window_host_win.cc b/ui/aura/remote_root_window_host_win.cc
index 71411b0adaae5f793bcb81ab11479a6d45b6de91..566f80300fa646505f9c2088a35773a8d6bf1159 100644
--- a/ui/aura/remote_root_window_host_win.cc
+++ b/ui/aura/remote_root_window_host_win.cc
@@ -107,6 +107,13 @@ bool RemoteRootWindowHostWin::ConfineCursorToRootWindow() {
   return true;
 }
 
+bool RemoteRootWindowHostWin::CopyAreaToSkCanvas(const gfx::Rect& source_bounds,
+                                                 const gfx::Point& dest_offset,
+                                                 SkCanvas* canvas) {
+  NOTIMPLEMENTED();
+  return false;
+}
+
 bool RemoteRootWindowHostWin::GrabSnapshot(
     const gfx::Rect& snapshot_bounds,
     std::vector<unsigned char>* png_representation) {