[Sync] Add support for sync Persistence Errors

chrome/browser/sync/glue/bookmark_model_associator.cc

Index: chrome/browser/sync/glue/bookmark_model_associator.cc
diff --git a/chrome/browser/sync/glue/bookmark_model_associator.cc b/chrome/browser/sync/glue/bookmark_model_associator.cc
index 846d3e2955ca37e85cb2b923c07d96db00f32f92..2782ec22efe671c04c7f527c74d10e1970024d19 100644
--- a/chrome/browser/sync/glue/bookmark_model_associator.cc
+++ b/chrome/browser/sync/glue/bookmark_model_associator.cc
@@ -364,7 +364,10 @@ bool BookmarkModelAssociator::GetSyncIdForTaggedNode(const std::string& tag,
 syncer::SyncError BookmarkModelAssociator::AssociateModels(
     syncer::SyncMergeResult* local_merge_result,
     syncer::SyncMergeResult* syncer_merge_result) {
-  CheckModelSyncState(local_merge_result, syncer_merge_result);
+  syncer::SyncError error = CheckModelSyncState(local_merge_result,
+                                                syncer_merge_result);
+  if (error.IsSet())
+    return error;
 
   scoped_ptr<ScopedAssociationUpdater> association_updater(
       new ScopedAssociationUpdater(bookmark_model_));
@@ -702,16 +705,16 @@ bool BookmarkModelAssociator::CryptoReadyIfNecessary() {
       trans.GetCryptographer()->is_ready();
 }
 
-void BookmarkModelAssociator::CheckModelSyncState(
+syncer::SyncError BookmarkModelAssociator::CheckModelSyncState(
     syncer::SyncMergeResult* local_merge_result,
     syncer::SyncMergeResult* syncer_merge_result) const {
   std::string version_str;
   if (bookmark_model_->root_node()->GetMetaInfo(kBookmarkTransactionVersionKey,
                                                 &version_str)) {
     syncer::ReadTransaction trans(FROM_HERE, user_share_);
-    int64 native_version;
+    int64 native_version = syncer::syncable::kInvalidTransactionVersion;
     if (!base::StringToInt64(version_str, &native_version))
-      return;
+      return syncer::SyncError();
     local_merge_result->set_pre_association_version(native_version);
 
     int64 sync_version = trans.GetModelVersion(syncer::BOOKMARKS);
@@ -721,11 +724,21 @@ void BookmarkModelAssociator::CheckModelSyncState(
       UMA_HISTOGRAM_ENUMERATION("Sync.LocalModelOutOfSync",
                                 ModelTypeToHistogramInt(syncer::BOOKMARKS),
                                 syncer::MODEL_TYPE_COUNT);
+
       // Clear version on bookmark model so that we only report error once.
       bookmark_model_->DeleteNodeMetaInfo(bookmark_model_->root_node(),
                                           kBookmarkTransactionVersionKey);
+
+      // If the native version is higher, there was a sync persistence failure,
+      // and we need to delay association until after a GetUpdates.
+      if (sync_version < native_version) {
+        DVLOG(1) << "Native version (" << native_version << ") does not match "
+                 << "sync version (" << sync_version << ").";
+        // TODO(zea): return a persistence error here.
+      }
     }
   }
+  return syncer::SyncError();
 }
 
 }  // namespace browser_sync