Fix some migration-related bugs

chrome/browser/sync/backend_migrator.h

Index: chrome/browser/sync/backend_migrator.h
diff --git a/chrome/browser/sync/backend_migrator.h b/chrome/browser/sync/backend_migrator.h
index 4688ce63d72dddb65f35826f8aade9170b16981f..2a5226a8f9555c925a8c4a44f4bd5b0082e26835 100644
--- a/chrome/browser/sync/backend_migrator.h
+++ b/chrome/browser/sync/backend_migrator.h
@@ -33,7 +33,7 @@ class MigrationObserver {
 
 // A class to perform migration of a datatype pursuant to the 'MIGRATION_DONE'
 // code in the sync protocol definition (protocol/sync.proto).
-class BackendMigrator : public content::NotificationObserver {
+class BackendMigrator {
  public:
   enum State {
     IDLE,
@@ -60,13 +60,12 @@ class BackendMigrator : public content::NotificationObserver {
   bool HasMigrationObserver(MigrationObserver* observer) const;
   void RemoveMigrationObserver(MigrationObserver* observer);
 
-  // content::NotificationObserver implementation.
-  virtual void Observe(int type,
-                       const content::NotificationSource& source,
-                       const content::NotificationDetails& details) OVERRIDE;
-
   State state() const;
 
+  // Called from ProfileSyncService to notify us of configure done.
+  // Note: We receive these notificiations only when our state is not IDLE.
+  void OnConfigureDone(const DataTypeManager::ConfigureResult& result);
+
   // Returns the types that are currently pending migration (if any).
   syncable::ModelTypeSet GetPendingMigrationTypesForTest() const;
 
@@ -82,8 +81,8 @@ class BackendMigrator : public content::NotificationObserver {
   // Restarts migration, interrupting any existing migration.
   void RestartMigration();
 
-  // Called by Observe().
-  void OnConfigureDone(const DataTypeManager::ConfigureResult& result);
+  // Called by OnConfigureDone().
+  void OnConfigureDoneImpl(const DataTypeManager::ConfigureResult& result);
 
   const std::string name_;
   sync_api::UserShare* user_share_;
@@ -92,8 +91,6 @@ class BackendMigrator : public content::NotificationObserver {
 
   State state_;
 
-  content::NotificationRegistrar registrar_;
-
   ObserverList<MigrationObserver> migration_observers_;
 
   syncable::ModelTypeSet to_migrate_;