Fixes _NET_ACTIVE_WINDOW support check in order to not always return no.

ui/views/widget/desktop_aura/x11_desktop_handler.h

 // 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.
 
 #ifndef UI_VIEWS_WIDGET_DESKTOP_AURA_X11_DESKTOP_HANDLER_H_
 #define UI_VIEWS_WIDGET_DESKTOP_AURA_X11_DESKTOP_HANDLER_H_
 
 #include <X11/Xlib.h>
 // Get rid of a macro from Xlib.h that conflicts with Aura's RootWindow class.
 #undef RootWindow
@@ skipping 33 matching lines @@
   // dispatcher. The window dispatcher sends these events to here.
   void ProcessXEvent(const base::NativeEvent& event);
 
   // Overridden from MessagePumpDispatcher:
   virtual bool Dispatch(const base::NativeEvent& event) OVERRIDE;
 
   // Overridden from aura::EnvObserver:
   virtual void OnWindowInitialized(aura::Window* window) OVERRIDE;
   virtual void OnWillDestroyEnv() OVERRIDE;
 
+  // Allows to override wm_supports_active_window_ value for tests. If the WM
+  // supports _NET_ACTIVE_WINDOW, activation is async otherwise it is sync.
+  void SetWMSupportsActiveWindowForTests(bool value) {
+    wm_supports_active_window_ = value;
+  }
+
  private:
   explicit X11DesktopHandler();
   virtual ~X11DesktopHandler();
 
   // Handles changes in activation.
   void OnActiveWindowChanged(::Window window);
 
   // The display and the native X window hosting the root window.
   XDisplay* xdisplay_;
 
   // The native root window.
   ::Window x_root_window_;
 
   // The activated window.
   ::Window current_window_;
 
   ui::X11AtomCache atom_cache_;
 
   bool wm_supports_active_window_;
 
   DISALLOW_COPY_AND_ASSIGN(X11DesktopHandler);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_DESKTOP_AURA_X11_DESKTOP_HANDLER_H_