Introduce TabRestoreServiceClient and //chrome implementation.

components/sessions.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': {
     # Core sources shared by sessions_content and sessions_ios. These can't
     # be a separate shared library since one symbol is implemented higher up in
     # the sessions_content/ios layer.
     'sessions_core_sources': [
       'sessions/base_session_service.cc',
       'sessions/base_session_service.h',
       'sessions/base_session_service_commands.cc',
       'sessions/base_session_service_commands.h',
       'sessions/base_session_service_delegate.h',
       'sessions/core/serialized_navigation_driver.h',
+      'sessions/core/session_constants.cc',
+      'sessions/core/session_constants.h',
+      'sessions/core/tab_restore_service_client.h',
       'sessions/serialized_navigation_entry.cc',
       'sessions/serialized_navigation_entry.h',
       'sessions/session_backend.cc',
       'sessions/session_backend.h',
       'sessions/session_command.cc',
       'sessions/session_command.h',
       'sessions/session_id.cc',
       'sessions/session_id.h',
       'sessions/session_service_commands.cc',
       'sessions/session_service_commands.h',
@@ skipping 93 matching lines @@
             'sessions/ios/ios_serialized_navigation_builder.h',
             'sessions/ios/ios_serialized_navigation_driver.cc',
             'sessions/ios/ios_serialized_navigation_driver.h',
           ],
         },
       ],
     }],
   ],
 
 }