Makes PlatformEventSource creation in Env conditional

ui/aura/test/aura_test_helper.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/aura/test/aura_test_helper.h"
 
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/client/default_capture_client.h"
@@ skipping 37 matching lines @@
 AuraTestHelper::~AuraTestHelper() {
   CHECK(setup_called_)
       << "AuraTestHelper::SetUp() never called.";
   CHECK(teardown_called_)
       << "AuraTestHelper::TearDown() never called.";
 }
 
 void AuraTestHelper::SetUp() {
   setup_called_ = true;
 
-  Env::CreateInstance();
+  Env::CreateInstance(true);
   // Unit tests generally don't want to query the system, rather use the state
   // from RootWindow.
   EnvTestHelper(Env::GetInstance()).SetInputStateLookup(
       scoped_ptr<InputStateLookup>());
 
   ui::InitializeInputMethodForTesting();
 
   test_screen_.reset(TestScreen::Create());
   gfx::Screen::SetScreenInstance(gfx::SCREEN_TYPE_NATIVE, test_screen_.get());
   host_.reset(test_screen_->CreateHostForPrimaryDisplay());
@@ skipping 35 matching lines @@
 
 void AuraTestHelper::RunAllPendingInMessageLoop() {
   // TODO(jbates) crbug.com/134753 Find quitters of this RunLoop and have them
   //              use run_loop.QuitClosure().
   base::RunLoop run_loop;
   run_loop.RunUntilIdle();
 }
 
 }  // namespace test
 }  // namespace aura