[Sync] Special case nigori when calculating commit id's.

chrome/browser/sync/engine/get_commit_ids_command.cc

Index: chrome/browser/sync/engine/get_commit_ids_command.cc
diff --git a/chrome/browser/sync/engine/get_commit_ids_command.cc b/chrome/browser/sync/engine/get_commit_ids_command.cc
index 3000649c44510ece1d7c26f5cfde0c6493901ef1..4c280ecd644401982bb3e69e71a8fe24d01fff18 100644
--- a/chrome/browser/sync/engine/get_commit_ids_command.cc
+++ b/chrome/browser/sync/engine/get_commit_ids_command.cc
@@ -94,7 +94,11 @@ bool IsEntryReadyForCommit(const syncable::ModelTypeSet& encrypted_types,
   }
 
   syncable::ModelType type = entry.GetModelType();
-  if (encrypted_types.count(type) > 0 &&
+  // We special case the nigori node because even though it is considered an
+  // "encrypted type", not all nigori node changes require valid encryption
+  // (ex: sync_tabs).
+  if (type != syncable::NIGORI &&
+      encrypted_types.count(type) > 0 &&
       (passphrase_missing ||
        syncable::EntryNeedsEncryption(encrypted_types, entry))) {
     // This entry requires encryption but is not properly encrypted (possibly