Handle birthday errors by disabling sync and deleting sync data.

chrome/browser/sync/glue/sync_backend_host.h

Index: chrome/browser/sync/glue/sync_backend_host.h
===================================================================
--- chrome/browser/sync/glue/sync_backend_host.h	(revision 52107)
+++ chrome/browser/sync/glue/sync_backend_host.h	(working copy)
@@ -58,6 +58,10 @@
   // credentials to be provided. See SyncBackendHost::Authenticate for details.
   virtual void OnAuthError() = 0;
 
+  // We are no longer permitted to communicate with the server. Sync should
+  // be disabled and state cleaned up at once.
+  virtual void OnStopSyncingPermanently() = 0;
+
  protected:
   // Don't delete through SyncFrontend interface.
   virtual ~SyncFrontend() {
@@ -230,6 +234,7 @@
     virtual void OnPassphraseAccepted();
     virtual void OnPaused();
     virtual void OnResumed();
+    virtual void OnStopSyncingPermanently();
 
     struct DoInitializeOptions {
       DoInitializeOptions(
@@ -374,6 +379,8 @@
     void HandleSyncCycleCompletedOnFrontendLoop(
         sessions::SyncSessionSnapshot* snapshot);
 
+    void HandleStopSyncingPermanentlyOnFrontendLoop();
+
     // Called from Core::OnInitializationComplete to handle updating
     // frontend thread components.
     void HandleInitalizationCompletedOnFrontendLoop();