sync: Introduce CryptographerProvider interface

sync/sync_core.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.
 
 {
   'include_dirs': [
     '..',
   ],
   'defines': [
     'SYNC_IMPLEMENTATION',
@@ skipping 30 matching lines @@
     'engine/commit_contributor.h',
     'engine/commit.h',
     'engine/commit_processor.cc',
     'engine/commit_processor.h',
     'engine/commit_util.cc',
     'engine/commit_util.h',
     'engine/conflict_resolver.cc',
     'engine/conflict_resolver.h',
     'engine/conflict_util.cc',
     'engine/conflict_util.h',
+    'engine/cryptographer_provider.cc',
+    'engine/cryptographer_provider.h',
     'engine/directory_commit_contribution.cc',
     'engine/directory_commit_contribution.h',
     'engine/directory_commit_contributor.cc',
     'engine/directory_commit_contributor.h',
+    'engine/directory_cryptographer_provider.cc',
+    'engine/directory_cryptographer_provider.h',
     'engine/directory_update_handler.cc',
     'engine/directory_update_handler.h',
     'engine/entity_tracker.cc',
     'engine/entity_tracker.h',
     'engine/get_commit_ids.cc',
     'engine/get_commit_ids.h',
     'engine/get_updates_delegate.cc',
     'engine/get_updates_delegate.h',
     'engine/get_updates_processor.cc',
     'engine/get_updates_processor.h',
@@ skipping 146 matching lines @@
     'util/get_session_name_win.cc',
     'util/get_session_name_win.h',
     'util/logging.cc',
     'util/logging.h',
     'util/nigori.cc',
     'util/nigori.h',
     'util/time.cc',
     'util/time.h',
   ],
 }