Do not allow GuestViewManager to (re)use an instance ID that was already removed.

chrome/chrome_tests_unit.gypi

 # Copyright 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.
 {
   'targets': [
     {
       # This target contains mocks and test utilities that don't belong in
       # production libraries but are used by more than one test executable.
       'target_name': 'test_support_common',
       'type': 'static_library',
@@ skipping 581 matching lines @@
         'browser/autocomplete/autocomplete_result_unittest.cc',
         'browser/autocomplete/bookmark_provider_unittest.cc',
         'browser/autocomplete/builtin_provider_unittest.cc',
         'browser/autocomplete/extension_app_provider_unittest.cc',
         'browser/autocomplete/history_quick_provider_unittest.cc',
         'browser/autocomplete/history_url_provider_unittest.cc',
         'browser/autocomplete/keyword_provider_unittest.cc',
         'browser/autocomplete/search_provider_unittest.cc',
         'browser/autocomplete/shortcuts_backend_unittest.cc',
         'browser/autocomplete/shortcuts_provider_unittest.cc',
-        'browser/autocomplete/zero_suggest_provider_unittest.cc',
+        'browser/autocomplete/zero_suggest_provider_unittest.cc',
         'browser/autofill/autofill_cc_infobar_delegate_unittest.cc',
         'browser/background/background_application_list_model_unittest.cc',
         'browser/background/background_contents_service_unittest.cc',
         'browser/background/background_mode_manager_unittest.cc',
         'browser/bookmarks/bookmark_html_writer_unittest.cc',
         'browser/browser_about_handler_unittest.cc',
         'browser/browser_commands_unittest.cc',
         'browser/browsing_data/browsing_data_appcache_helper_unittest.cc',
         'browser/browsing_data/browsing_data_cookie_helper_unittest.cc',
         'browser/browsing_data/browsing_data_database_helper_unittest.cc',
@@ skipping 367 matching lines @@
         'browser/external_protocol/external_protocol_handler_unittest.cc',
         'browser/favicon/favicon_handler_unittest.cc',
         'browser/file_select_helper_unittest.cc',
         'browser/first_run/first_run_unittest.cc',
         'browser/geolocation/chrome_geolocation_permission_context_unittest.cc',
         'browser/global_keyboard_shortcuts_mac_unittest.mm',
         'browser/google/google_search_counter_unittest.cc',
         'browser/google/google_update_settings_unittest.cc',
         'browser/google/google_url_tracker_unittest.cc',
         'browser/google/google_util_unittest.cc',
+        'browser/guest_view/guest_view_manager_unittest.cc',
         'browser/history/android/android_cache_database_unittest.cc',
         'browser/history/android/android_history_provider_service_unittest.cc',
         'browser/history/android/android_history_types_unittest.cc',
         'browser/history/android/android_provider_backend_unittest.cc',
         'browser/history/android/android_urls_database_unittest.cc',
         'browser/history/android/bookmark_model_sql_handler_unittest.cc',
         'browser/history/android/sqlite_cursor_unittest.cc',
         'browser/history/android/urls_sql_handler_unittest.cc',
         'browser/history/android/visit_sql_handler_unittest.cc',
         'browser/history/expire_history_backend_unittest.cc',
@@ skipping 1819 matching lines @@
             'unit_tests.isolate',
           ],
           'sources': [
             'unit_tests.isolate',
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }