mus: Let clients set the cursor of their window.

ui/platform_window/x11/x11_window.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/platform_window/x11/x11_window.h"
 
 #include <X11/extensions/XInput2.h>
 #include <X11/Xatom.h>
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
@@ skipping 239 matching lines @@
 void X11Window::ReleaseCapture() {}
 
 void X11Window::ToggleFullscreen() {}
 
 void X11Window::Maximize() {}
 
 void X11Window::Minimize() {}
 
 void X11Window::Restore() {}
 
-void X11Window::SetCursor(PlatformCursor cursor) {}
+void X11Window::SetCursor(PlatformCursor cursor) {
+  XDefineCursor(xdisplay_, xwindow_, cursor);
+}
 
 void X11Window::MoveCursorTo(const gfx::Point& location) {}
 
 void X11Window::ConfineCursorToBounds(const gfx::Rect& bounds) {
 }
 
 PlatformImeController* X11Window::GetPlatformImeController() {
   return nullptr;
 }
 
@@ skipping 105 matching lines @@
 }
 
 namespace test {
 
 void SetUseOverrideRedirectWindowByDefault(bool override_redirect) {
   g_override_redirect = override_redirect;
 }
 
 }  // namespace test
 }  // namespace ui