Implement cursor compositing mode on Ash

ash/shell.cc

Index: ash/shell.cc
diff --git a/ash/shell.cc b/ash/shell.cc
index 986612e3a67ce97e60826a8f5e988d4327b9bd43..da9ab7defa739f9f99c94f14e60bea46a40ea6f5 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -560,6 +560,16 @@ void Shell::DoInitialWorkspaceAnimation() {
       DoInitialAnimation();
 }
 
+#if defined(OS_CHROMEOS) && defined(USE_X11)
+void Shell::SetCursorCompositingEnabled(bool enabled) {
+  if (is_cursor_compositing_enabled_ != enabled) {
+    display_controller_->SetCursorCompositingEnabled(enabled);
+    cursor_manager_.SetNativeCursorEnabled(!enabled);
+    is_cursor_compositing_enabled_ = enabled;
+  }
+}
+#endif
+
 ////////////////////////////////////////////////////////////////////////////////
 // Shell, private: