Enable immersive fullscreen on Windows Ash.

chrome/browser/ui/views/tabs/tab_drag_controller_interactive_uitest.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/tabs/tab_drag_controller_interactive_uitest.h"
 
 #include "ash/wm/window_state.h"
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/command_line.h"
@@ skipping 1765 matching lines @@
   ASSERT_FALSE(tab_strip->IsDragSessionActive());
   ASSERT_FALSE(TabDragController::IsActive());
   EXPECT_EQ("0 100", IDString(browser2->tab_strip_model()));
   EXPECT_EQ("1", IDString(browser()->tab_strip_model()));
 
   // Source browser should still be maximized, target should not
   EXPECT_TRUE(browser()->window()->IsMaximized());
   EXPECT_FALSE(browser2->window()->IsMaximized());
 }
 
-// Immersive fullscreen is ChromeOS only.
+// Immersive fullscreen is Ash only.  However, Windows Ash does not support
+// multiple displays.
 #if defined(OS_CHROMEOS)
 // TODO(sky,sad): Disabled as it fails due to resize locks with a real
 // compositor. crbug.com/331924
 #define MAYBE_DragTabToImmersiveBrowserOnSeparateDisplay \
   DISABLED_DragTabToImmersiveBrowserOnSeparateDisplay
 // Drags from a restored browser to an immersive fullscreen browser on a
 // second display and releases input.
 IN_PROC_BROWSER_TEST_P(DetachToBrowserInSeparateDisplayTabDragControllerTest,
                        MAYBE_DragTabToImmersiveBrowserOnSeparateDisplay) {
   // Add another tab.
@@ skipping 534 matching lines @@
                         DetachToDockedTabDragControllerTest,
                         ::testing::Values("mouse", "mouse docked"));
 INSTANTIATE_TEST_CASE_P(TabDragging,
                         DetachToBrowserTabDragControllerTestTouch,
                         ::testing::Values("touch", "touch docked"));
 #else
 INSTANTIATE_TEST_CASE_P(TabDragging,
                         DetachToBrowserTabDragControllerTest,
                         ::testing::Values("mouse"));
 #endif