Separate SyncData methods into three groups, local, remote, and common.

chrome/browser/extensions/extension_sync_bundle.cc

Index: chrome/browser/extensions/extension_sync_bundle.cc
diff --git a/chrome/browser/extensions/extension_sync_bundle.cc b/chrome/browser/extensions/extension_sync_bundle.cc
index 9d91af92cc71df98cfa160aa71a34da7ce1d4ed3..facac2295cb7f596b2f08341f261883489af5a91 100644
--- a/chrome/browser/extensions/extension_sync_bundle.cc
+++ b/chrome/browser/extensions/extension_sync_bundle.cc
@@ -59,12 +59,13 @@ void ExtensionSyncBundle::ProcessDeletion(
 
 syncer::SyncChange ExtensionSyncBundle::CreateSyncChange(
     const syncer::SyncData& sync_data) {
-  if (HasExtensionId(sync_data.GetTag())) {
+  const syncer::SyncDataLocal sync_data_local(sync_data);
+  if (HasExtensionId(sync_data_local.GetTag())) {
     return syncer::SyncChange(FROM_HERE,
                               syncer::SyncChange::ACTION_UPDATE,
                               sync_data);
   } else {
-    AddExtension(sync_data.GetTag());
+    AddExtension(sync_data_local.GetTag());
     return syncer::SyncChange(FROM_HERE,
                               syncer::SyncChange::ACTION_ADD,
                               sync_data);