[Sync] MergeSyncData implementation for Autocomplete.

components/autofill/core/browser/webdata/autocomplete_sync_bridge.cc

 // Copyright 2016 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 "components/autofill/core/browser/webdata/autocomplete_sync_bridge.h"
 
 #include <algorithm>
 #include <set>
 #include <unordered_set>
 #include <utility>
@@ skipping 125 matching lines @@
     }
 
     const AutofillEntry remote = CreateAutofillEntry(specifics);
     DCHECK_EQ(storage_key, GetStorageKeyFromModel(remote.key()));
 
     Optional<AutofillEntry> local;
     if (!ReadEntry(remote.key(), &local)) {
       return ModelError(FROM_HERE, "Failed reading from WebDatabase.");
     } else if (!local) {
       save_to_local_.push_back(remote);
-    } else if (remote != local.value()) {
-      if (specifics.usage_timestamp().empty()) {
-        // Skip merging if there are no timestamps. We don't want to wipe out
-        // a local value of |date_created| if the remote copy is oddly formed.
-        save_to_sync_.push_back(local.value());
-      } else {
-        const AutofillEntry merged = MergeEntryDates(local.value(), remote);
-        save_to_local_.push_back(merged);
-        save_to_sync_.push_back(merged);
+    } else {
+      unique_to_local_.erase(local.value());
+      if (remote != local.value()) {
+        if (specifics.usage_timestamp().empty()) {
+          // Skip merging if there are no timestamps. We don't want to wipe out
+          // a local value of |date_created| if the remote copy is oddly formed.
+          save_to_sync_.push_back(local.value());
+        } else {
+          const AutofillEntry merged = MergeEntryDates(local.value(), remote);
+          save_to_local_.push_back(merged);
+          save_to_sync_.push_back(merged);
+        }
       }
-      unique_to_local_.erase(local.value());
     }
     return {};
   }
 
   Optional<ModelError> IncorporateRemoteDelete(const std::string& storage_key) {
     AutofillKey key;
     if (!ParseStorageKey(storage_key, &key)) {
       return ModelError(FROM_HERE, "Failed parsing storage key.");
     }
     delete_from_local_.insert(key);
@@ skipping 144 matching lines @@
   DCHECK(thread_checker_.CalledOnValidThread());
   return base::MakeUnique<AutofillMetadataChangeList>(GetAutofillTable(),
                                                       syncer::AUTOFILL);
 }
 
 Optional<syncer::ModelError> AutocompleteSyncBridge::MergeSyncData(
     std::unique_ptr<MetadataChangeList> metadata_change_list,
     EntityDataMap entity_data_map) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
-  // TODO(skym, crbug.com/680218): Uncomment and add unit tests.
-  /*SyncDifferenceTracker tracker(GetAutofillTable());
+  SyncDifferenceTracker tracker(GetAutofillTable());
   for (auto kv : entity_data_map) {
     DCHECK(kv.second->specifics.has_autofill());
     RETURN_IF_ERROR(tracker.IncorporateRemoteSpecifics(
         kv.first, kv.second->specifics.autofill()));
   }
 
   RETURN_IF_ERROR(tracker.FlushToLocal(web_data_backend_));
   RETURN_IF_ERROR(tracker.FlushToSync(true, std::move(metadata_change_list),
                                 change_processor()));
   web_data_backend_->RemoveExpiredFormElements();
-  web_data_backend_->NotifyThatSyncHasStarted(syncer::AUTOFILL);*/
+  web_data_backend_->NotifyThatSyncHasStarted(syncer::AUTOFILL);
   return {};
 }
 
 Optional<ModelError> AutocompleteSyncBridge::ApplySyncChanges(
     std::unique_ptr<MetadataChangeList> metadata_change_list,
     EntityChangeList entity_changes) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   SyncDifferenceTracker tracker(GetAutofillTable());
   for (const EntityChange& change : entity_changes) {
@@ skipping 124 matching lines @@
     const AutofillChangeList& changes) {
   DCHECK(thread_checker_.CalledOnValidThread());
   ActOnLocalChanges(changes);
 }
 
 AutofillTable* AutocompleteSyncBridge::GetAutofillTable() const {
   return AutofillTable::FromWebDatabase(web_data_backend_->GetDatabase());
 }
 
 }  // namespace autofill