Add a Restore() method to ValueStore and make StorageAPI use it

chrome/browser/extensions/api/storage/syncable_settings_storage.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/extensions/api/storage/syncable_settings_storage.h"
 
 #include "base/strings/stringprintf.h"
 #include "chrome/browser/extensions/api/storage/settings_namespace.h"
 #include "chrome/browser/extensions/api/storage/settings_sync_processor.h"
 #include "chrome/browser/extensions/api/storage/settings_sync_util.h"
@@ skipping 104 matching lines @@
 ValueStore::WriteResult SyncableSettingsStorage::Clear() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
   WriteResult result = delegate_->Clear();
   if (result->HasError()) {
     return result.Pass();
   }
   SyncResultIfEnabled(result);
   return result.Pass();
 }
 
+bool SyncableSettingsStorage::Restore() {
+  // If we're syncing, stop - we don't want to push the deletion of any data.
+  // At next startup, when we start up the sync service, we'll get back any
+  // data which was stored intact on Sync.
+  // TODO (rdevlin.cronin): Investigate if there's a way we can trigger
+  // MergeDataAndStartSyncing() to immediately get back any data we can.
+  StopSyncing();
+  return delegate_->Restore();
+}
+
+bool SyncableSettingsStorage::RestoreKey(const std::string& key) {
+  // If we're syncing, stop - we don't want to push the deletion of any data.
+  // At next startup, when we start up the sync service, we'll get back any
+  // data which was stored intact on Sync.
+  // TODO (rdevlin.cronin): Investigate if there's a way we can trigger
+  // MergeDataAndStartSyncing() to immediately get back any data we can.
+  StopSyncing();
+  return delegate_->RestoreKey(key);
+}
+
 void SyncableSettingsStorage::SyncResultIfEnabled(
     const ValueStore::WriteResult& result) {
   if (result->changes().empty())
     return;
 
   if (sync_processor_.get()) {
     syncer::SyncError error = sync_processor_->SendChanges(result->changes());
     if (error.IsSet())
       StopSyncing();
   } else {
@@ skipping 259 matching lines @@
         syncer::SyncError::DATATYPE_ERROR,
         base::StringPrintf("Error pushing sync remove to local settings: %s",
             result->error().message.c_str()),
         sync_processor_->type());
   }
   changes->push_back(ValueStoreChange(key, old_value, NULL));
   return syncer::SyncError();
 }
 
 }  // namespace extensions