[Sync] Add sync api support for context changes

chrome/browser/sync/glue/generic_change_processor.cc

 // Copyright (c) 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.
 
 #include "chrome/browser/sync/glue/generic_change_processor.h"
 
 #include "base/location.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "content/public/browser/browser_thread.h"
@@ skipping 149 matching lines @@
 }
 
 syncer::SyncDataList GenericChangeProcessor::GetAllSyncData(
     syncer::ModelType type) const {
   // This is slow / memory intensive.  Should be used sparingly by datatypes.
   syncer::SyncDataList data;
   GetAllSyncDataReturnError(type, &data);
   return data;
 }
 
+syncer::SyncError GenericChangeProcessor::UpdateDataTypeContext(
+    syncer::ModelType type,
+    const std::string& context) {
+  NOTIMPLEMENTED();
+  return syncer::SyncError();
+}
+
 syncer::SyncError GenericChangeProcessor::GetAllSyncDataReturnError(
     syncer::ModelType type,
     syncer::SyncDataList* current_sync_data) const {
   DCHECK(CalledOnValidThread());
   std::string type_name = syncer::ModelTypeToString(type);
   syncer::ReadTransaction trans(FROM_HERE, share_handle());
   syncer::ReadNode root(&trans);
   if (root.InitByTagLookup(syncer::ModelTypeToRootTag(type)) !=
           syncer::BaseNode::INIT_OK) {
     syncer::SyncError error(FROM_HERE,
@@ skipping 437 matching lines @@
 void GenericChangeProcessor::StartImpl(Profile* profile) {
   DCHECK(CalledOnValidThread());
 }
 
 syncer::UserShare* GenericChangeProcessor::share_handle() const {
   DCHECK(CalledOnValidThread());
   return share_handle_;
 }
 
 }  // namespace browser_sync