Enable CursorManager::LockCursor to lock cursor visibility.

ui/aura/desktop/desktop_cursor_client.h

Index: ui/aura/desktop/desktop_cursor_client.h
diff --git a/ui/aura/desktop/desktop_cursor_client.h b/ui/aura/desktop/desktop_cursor_client.h
index 0bc49c4390bc7bf4d2a28a8ba7bbeb900abc7175..0f292e2c38ce2b2b56017d8403a2dc684bac62c6 100644
--- a/ui/aura/desktop/desktop_cursor_client.h
+++ b/ui/aura/desktop/desktop_cursor_client.h
@@ -29,11 +29,16 @@ class AURA_EXPORT DesktopCursorClient : public client::CursorClient {
   virtual void ShowCursor(bool show) OVERRIDE;
   virtual bool IsCursorVisible() const OVERRIDE;
   virtual void SetDeviceScaleFactor(float device_scale_factor) OVERRIDE;
+  virtual void LockCursor() OVERRIDE;
+  virtual void UnlockCursor() OVERRIDE;
 
  private:
   aura::RootWindow* root_window_;
   scoped_ptr<ui::CursorLoader> cursor_loader_;
 
+  gfx::NativeCursor current_cursor_;
+  bool cursor_visible_;
+
   DISALLOW_COPY_AND_ASSIGN(DesktopCursorClient);
 };