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

chrome/browser/extensions/api/storage/syncable_settings_storage.cc

Index: chrome/browser/extensions/api/storage/syncable_settings_storage.cc
diff --git a/chrome/browser/extensions/api/storage/syncable_settings_storage.cc b/chrome/browser/extensions/api/storage/syncable_settings_storage.cc
index db877c6882bad8e34362faf01c7b9974e48fd2cc..ff2b5f79300eabe637e8942628551a22c0723083 100644
--- a/chrome/browser/extensions/api/storage/syncable_settings_storage.cc
+++ b/chrome/browser/extensions/api/storage/syncable_settings_storage.cc
@@ -122,6 +122,26 @@ ValueStore::WriteResult SyncableSettingsStorage::Clear() {
   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())