Enable immersive fullscreen on Windows Ash.

chrome/browser/ui/views/frame/browser_non_client_frame_view_ash_browsertest.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 "chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.h"
 
 #include "ash/ash_constants.h"
 #include "ash/ash_switches.h"
 #include "ash/frame/caption_buttons/frame_caption_button_container_view.h"
 #include "ash/frame/header_painter.h"
@@ skipping 77 matching lines @@
   {
     scoped_ptr<FullscreenNotificationObserver> waiter(
         new FullscreenNotificationObserver());
     chrome::ToggleFullscreenMode(browser());
     waiter->Wait();
   }
   EXPECT_TRUE(frame_view->ShouldPaint());
   EXPECT_TRUE(frame_view->caption_button_container_->visible());
 }
 
-// Immersive fullscreen is CrOS only for now.
+// TODO(zturner): Change this to USE_ASH after fixing the test on Windows.
 #if defined(OS_CHROMEOS)
 IN_PROC_BROWSER_TEST_F(BrowserNonClientFrameViewAshTest, ImmersiveFullscreen) {
   // We know we're using Views, so static cast.
   BrowserView* browser_view = static_cast<BrowserView*>(browser()->window());
   content::WebContents* web_contents = browser_view->GetActiveWebContents();
   Widget* widget = browser_view->GetWidget();
   // We know we're using Ash, so static cast.
   BrowserNonClientFrameViewAsh* frame_view =
       static_cast<BrowserNonClientFrameViewAsh*>(
           widget->non_client_view()->frame_view());
@@ skipping 83 matching lines @@
     waiter->Wait();
   }
   EXPECT_FALSE(immersive_mode_controller->IsEnabled());
   EXPECT_TRUE(frame_view->ShouldPaint());
   EXPECT_TRUE(frame_view->caption_button_container_->visible());
   EXPECT_FALSE(frame_view->UseImmersiveLightbarHeaderStyle());
   EXPECT_LT(Tab::GetImmersiveHeight(),
             frame_view->header_painter_->header_height());
 }
 #endif  // defined(OS_CHROMEOS)