Introduce the plumbing necessary to report Unrecoverable error from model safe workers.

chrome/browser/sync/engine/syncer_util.cc

Index: chrome/browser/sync/engine/syncer_util.cc
diff --git a/chrome/browser/sync/engine/syncer_util.cc b/chrome/browser/sync/engine/syncer_util.cc
index 8b8e5eff80bb41bf5fe99f6fe5bc01ec9de7d5d2..6efaf0c4c6513ba4da7f313d2467b6c662af4ab7 100644
--- a/chrome/browser/sync/engine/syncer_util.cc
+++ b/chrome/browser/sync/engine/syncer_util.cc
@@ -362,7 +362,8 @@ UpdateAttemptResponse SyncerUtil::AttemptToUpdateEntry(
     }
   }
 
-  SyncerUtil::UpdateLocalDataFromServerData(trans, entry);
+  if (!SyncerUtil::UpdateLocalDataFromServerData(trans, entry))
+    return FAILED_UPDATE;
 
   return SUCCESS;
 }
@@ -554,7 +555,7 @@ void SyncerUtil::SplitServerInformationIntoNewEntry(
 // This function is called on an entry when we can update the user-facing data
 // from the server data.
 // static
-void SyncerUtil::UpdateLocalDataFromServerData(
+bool SyncerUtil::UpdateLocalDataFromServerData(
     syncable::WriteTransaction* trans,
     syncable::MutableEntry* entry) {
   DCHECK(!entry->Get(IS_UNSYNCED));
@@ -572,11 +573,12 @@ void SyncerUtil::UpdateLocalDataFromServerData(
   } else {
     entry->Put(NON_UNIQUE_NAME, entry->Get(SERVER_NON_UNIQUE_NAME));
     entry->Put(PARENT_ID, entry->Get(SERVER_PARENT_ID));
-    CHECK(entry->Put(IS_DEL, false));
+    if (!entry->Put(IS_DEL, false))
+      return false;
     Id new_predecessor =
         entry->ComputePrevIdFromServerPosition(entry->Get(SERVER_PARENT_ID));
-    CHECK(entry->PutPredecessor(new_predecessor))
-        << " Illegal predecessor after converting from server position.";
+    if (!entry->PutPredecessor(new_predecessor))
+      return false;
   }
 
   entry->Put(CTIME, entry->Get(SERVER_CTIME));
@@ -584,6 +586,8 @@ void SyncerUtil::UpdateLocalDataFromServerData(
   entry->Put(BASE_VERSION, entry->Get(SERVER_VERSION));
   entry->Put(IS_DEL, entry->Get(SERVER_IS_DEL));
   entry->Put(IS_UNAPPLIED_UPDATE, false);
+
+  return true;
 }
 
 // static