Makes PlatformEventSource creation in Env conditional

ui/aura/demo/demo_main.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 "base/at_exit.h"
 #include "base/command_line.h"
 #include "base/i18n/icu_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "third_party/skia/include/core/SkXfermode.h"
@@ skipping 110 matching lines @@
 #endif
 
   // The ContextFactory must exist before any Compositors are created.
   scoped_ptr<ui::InProcessContextFactory> context_factory(
       new ui::InProcessContextFactory());
   ui::ContextFactory::SetInstance(context_factory.get());
 
   // Create the message-loop here before creating the root window.
   base::MessageLoopForUI message_loop;
 
-  aura::Env::CreateInstance();
+  aura::Env::CreateInstance(true);
   scoped_ptr<aura::TestScreen> test_screen(aura::TestScreen::Create());
   gfx::Screen::SetScreenInstance(gfx::SCREEN_TYPE_NATIVE, test_screen.get());
   scoped_ptr<aura::WindowTreeHost> host(
       test_screen->CreateHostForPrimaryDisplay());
   scoped_ptr<DemoWindowTreeClient> window_tree_client(
       new DemoWindowTreeClient(host->window()));
   aura::test::TestFocusClient focus_client;
   aura::client::SetFocusClient(host->window(), &focus_client);
 
   // Create a hierarchy of test windows.
@@ skipping 32 matching lines @@
 int main(int argc, char** argv) {
   CommandLine::Init(argc, argv);
 
   // The exit manager is in charge of calling the dtors of singleton objects.
   base::AtExitManager exit_manager;
 
   base::i18n::InitializeICU();
 
   return DemoMain();
 }