Improve check for whether _NET_ACTIVE_WINDOW is supported

ui/views/widget/desktop_aura/x11_desktop_handler.cc

 // Copyright (c) 2012 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/views/widget/desktop_aura/x11_desktop_handler.h"
 
 #include <X11/Xatom.h>
 #include <X11/Xlib.h>
 
 #include "base/message_loop/message_loop.h"
@@ skipping 40 matching lines @@
   if (ui::PlatformEventSource::GetInstance())
     ui::PlatformEventSource::GetInstance()->AddPlatformEventDispatcher(this);
   aura::Env::GetInstance()->AddObserver(this);
 
   XWindowAttributes attr;
   XGetWindowAttributes(xdisplay_, x_root_window_, &attr);
   XSelectInput(xdisplay_, x_root_window_,
                attr.your_event_mask | PropertyChangeMask |
                StructureNotifyMask | SubstructureNotifyMask);
 
-  ::Window active_window;
   wm_supports_active_window_ =
-    ui::GetXIDProperty(x_root_window_, "_NET_ACTIVE_WINDOW", &active_window) &&
-    active_window;
+      ui::WmSupportsHint(atom_cache_.GetAtom("_NET_ACTIVE_WINDOW"));
 }
 
 X11DesktopHandler::~X11DesktopHandler() {
   aura::Env::GetInstance()->RemoveObserver(this);
   if (ui::PlatformEventSource::GetInstance())
     ui::PlatformEventSource::GetInstance()->RemovePlatformEventDispatcher(this);
 }
 
 void X11DesktopHandler::ActivateWindow(::Window window) {
   if (current_window_ == window &&
@@ skipping 158 matching lines @@
     ui::XMenuList::GetInstance()->MaybeUnregisterMenu(window);
   }
 
   if (event_type == DestroyNotify) {
     // Notify the XForeignWindowManager that |window| has been destroyed.
     ui::XForeignWindowManager::GetInstance()->OnWindowDestroyed(window);
   }
 }
 
 }  // namespace views