Move constants used by history component to history namespace

components/history.gypi

 # Copyright 2014 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': [
     {
       # GN version: //components/history/core/browser
       'target_name': 'history_core_browser',
       'type': 'static_library',
@@ skipping 10 matching lines @@
         'favicon_base',
         'keyed_service_core',
         'query_parser',
       ],
       'sources': [
         # Note: sources list duplicated in GN build.
         'history/core/browser/history_backend_notifier.h',
         'history/core/browser/history_backend_observer.h',
         'history/core/browser/history_client.cc',
         'history/core/browser/history_client.h',
+        'history/core/browser/history_constants.cc',
+        'history/core/browser/history_constants.h',
         'history/core/browser/history_match.cc',
         'history/core/browser/history_match.h',
         'history/core/browser/history_service_observer.h',
         'history/core/browser/history_types.cc',
         'history/core/browser/history_types.h',
         'history/core/browser/in_memory_database.cc',
         'history/core/browser/in_memory_database.h',
         'history/core/browser/keyword_id.h',
         'history/core/browser/keyword_search_term.cc',
         'history/core/browser/keyword_search_term.h',
@@ skipping 58 matching lines @@
           ],
           'sources': [
             'history/core/android/android_history_types.cc',
             'history/core/android/android_history_types.h',
           ],
         },
       ],
     }],
   ],
 }