Instant: Use only one hidden WebContents per profile.

chrome/chrome_tests.gypi

 # Copyright 2013 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.
 {
   'variables' : {
     'pyautolib_sources': [
       'app/chrome_command_ids.h',
       'app/chrome_dll_resource.h',
       'common/automation_constants.h',
       'common/pref_names.cc',
@@ skipping 1365 matching lines @@
         'browser/ui/cocoa/extensions/extension_action_context_menu_browsertest.mm',
         'browser/ui/cocoa/extensions/extension_install_dialog_controller_browsertest.mm',
         'browser/ui/cocoa/extensions/extension_install_prompt_test_utils.h',
         'browser/ui/cocoa/extensions/extension_install_prompt_test_utils.mm',
         'browser/ui/cocoa/extensions/media_galleries_dialog_cocoa_browsertest.mm',
         'browser/ui/cocoa/find_bar/find_bar_browsertest.mm',
         'browser/ui/cocoa/location_bar/location_bar_view_mac_browsertest.mm',
         'browser/ui/cocoa/omnibox/omnibox_view_mac_browsertest.mm',
         'browser/ui/cocoa/one_click_signin_dialog_controller_browsertest.mm',
         'browser/ui/cocoa/ssl_client_certificate_selector_cocoa_browsertest.mm',
-        'browser/ui/cocoa/tab_contents/previewable_contents_controller_browsertest.mm',
+        'browser/ui/cocoa/tab_contents/overlayable_contents_controller_browsertest.mm',
         'browser/ui/cocoa/view_id_util_browsertest.mm',
         'browser/ui/find_bar/find_bar_host_browsertest.cc',
         'browser/ui/fullscreen/fullscreen_controller_browsertest.cc',
         'browser/ui/global_error/global_error_service_browsertest.cc',
         'browser/ui/gtk/bubble/bubble_gtk_browsertest.cc',
         'browser/ui/gtk/confirm_bubble_gtk_browsertest.cc',
         'browser/ui/gtk/location_bar_view_gtk_browsertest.cc',
         'browser/ui/gtk/one_click_signin_bubble_gtk_browsertest.cc',
         'browser/ui/gtk/view_id_util_browsertest.cc',
         'browser/ui/login/login_prompt_browsertest.cc',
@@ skipping 1761 matching lines @@
               # more details.
               'DebugInformationFormat': '3',
               'ProgramDataBaseFileName': '<(PRODUCT_DIR)/browser_tests.exe.pdb',
             },
           },
         },
       ],
     }],
   ],  # 'conditions'
 }