Implement cursor compositing mode on Ash

ui/views/corewm/cursor_manager.h

Index: ui/views/corewm/cursor_manager.h
diff --git a/ui/views/corewm/cursor_manager.h b/ui/views/corewm/cursor_manager.h
index 29f890ae6bd899d76ea75566801b8187a9523546..56c158735340443d32d418a17c67c3372f3e1b5b 100644
--- a/ui/views/corewm/cursor_manager.h
+++ b/ui/views/corewm/cursor_manager.h
@@ -61,6 +61,11 @@ class VIEWS_EXPORT CursorManager : public aura::client::CursorClient,
   virtual void RemoveObserver(
       aura::client::CursorClientObserver* observer) OVERRIDE;
 
+  // Toggles native cursor enabled/disabled.
+  // The native cursor is enabled by default.
+  // When disabled, native cursor is hidden even when cursor is visible.

[sky, 2014/02/06 01:33:21]

Doesn't HideCursor/ShowCursor do this? Why do we need this instead of that?

[hshi1, 2014/02/06 01:41:19]

This is intended to hide the native cursor at a lower level (X11) so that it
doesn't interfere with Ash cursor compositing. Otherwise the X11 cursor will be
drawn on top of the Ash desktop and occlude the composited cursor. We can't
simply call HideCursor() here because it will also cause Ash to hide the
composited cursor.

Ultimately I just need the call to arrive in
AshNativeCursorManager::SetNativeCursorEnabled, and this is rather cumbersome to
make several hoops. However I don't know if ash Shell can directly access the
AshNativeCursorManager.

+  void SetNativeCursorEnabled(bool enabled);
+
  private:
   // Overridden from NativeCursorManagerDelegate:
   virtual void CommitCursor(gfx::NativeCursor cursor) OVERRIDE;