Add routing info and unrecoverable error info to about:sync

chrome/browser/sync/engine/model_safe_worker.cc

Index: chrome/browser/sync/engine/model_safe_worker.cc
===================================================================
--- chrome/browser/sync/engine/model_safe_worker.cc	(revision 49216)
+++ chrome/browser/sync/engine/model_safe_worker.cc	(working copy)
@@ -20,4 +20,20 @@
   return it->second;
 }
 
+std::string ModelSafeGroupToString(ModelSafeGroup group) {
+  switch (group) {
+    case GROUP_UI:
+      return "GROUP_UI";
+    case GROUP_DB:
+      return "GROUP_DB";
+    case GROUP_HISTORY:
+      return "GROUP_HISTORY";
+    case GROUP_PASSIVE:
+      return "GROUP_PASSIVE";
+    default:
+      NOTREACHED();
+      return "INVALID";
+  }
+}
+
 }  // namespace browser_sync