Not for review: Support sync init with missing or corrupt store

chrome/browser/sync/glue/sync_backend_registrar.h

Index: chrome/browser/sync/glue/sync_backend_registrar.h
diff --git a/chrome/browser/sync/glue/sync_backend_registrar.h b/chrome/browser/sync/glue/sync_backend_registrar.h
index b70b33af7abbedfdb224aac731df60ec338e1a0a..8e0a15432242c782f04bb1a5d730468d9ecefcb5 100644
--- a/chrome/browser/sync/glue/sync_backend_registrar.h
+++ b/chrome/browser/sync/glue/sync_backend_registrar.h
@@ -34,12 +34,9 @@ class UIModelWorker;
 // events to the right processors.
 class SyncBackendRegistrar : public sync_api::SyncManager::ChangeDelegate {
  public:
-  // |initial_types| contains the initial set of types to sync
-  // (initially put in the passive group).  |name| is used for
-  // debugging.  Does not take ownership of |profile| or |sync_loop|.
-  // Must be created on the UI thread.
-  SyncBackendRegistrar(syncable::ModelTypeSet initial_types,
-                       const std::string& name,
+  // |name| is used for debugging.  Does not take ownership of |profile| or
+  // |sync_loop|.  Must be created on the UI thread.
+  SyncBackendRegistrar(const std::string& name,
                        Profile* profile,
                        MessageLoop* sync_loop);
 
@@ -56,6 +53,11 @@ class SyncBackendRegistrar : public sync_api::SyncManager::ChangeDelegate {
   // thread which the syncer pushes changes to).
   virtual ~SyncBackendRegistrar();
 
+  // Informs the SyncBackendRegistrar of the currently enabled set of types.
+  // These types will be placed in the passive group.  This function should be
+  // called exactly once during startup.
+  void SetInitialTypes(syncable::ModelTypeSet initial_types);

[rlarocque, 2012/06/04 20:07:09]

I'm not a fan of this two-stage init.  It may be possible to split this class in
two in order to avoid this, but I haven't tried.  

On the plus side, this is much simpler and safer than the other schemes I tried.
 There's no need for extra inter-thread communication with this approach.  That
does a lot to reduce the amount of new code and error-handling required.  

+
   // Returns whether or not we are currently syncing encryption keys.
   // Must be called on the UI thread.
   bool IsNigoriEnabled() const;