[Sync] Make BackendMigrator not wait for full sync cycles

chrome/browser/sync/profile_sync_service.h

Index: chrome/browser/sync/profile_sync_service.h
diff --git a/chrome/browser/sync/profile_sync_service.h b/chrome/browser/sync/profile_sync_service.h
index 0af7081470d24f4fc938ef66497ecb372cc6fb5c..fb5a24df85ffd25effa25ddd5310744c9315ca63 100644
--- a/chrome/browser/sync/profile_sync_service.h
+++ b/chrome/browser/sync/profile_sync_service.h
@@ -20,6 +20,7 @@
 #include "base/timer.h"
 #include "base/tracked.h"
 #include "chrome/browser/prefs/pref_member.h"
+#include "chrome/browser/sync/backend_migrator.h"
 #include "chrome/browser/sync/engine/model_safe_worker.h"
 #include "chrome/browser/sync/glue/data_type_controller.h"
 #include "chrome/browser/sync/glue/sync_backend_host.h"
@@ -43,7 +44,6 @@ class SigninManager;
 struct ChromeCookieDetails;
 
 namespace browser_sync {
-class BackendMigrator;
 class ChangeProcessor;
 class DataTypeManager;
 class JsController;
@@ -101,6 +101,7 @@ struct UserShare;
 //
 class ProfileSyncService : public browser_sync::SyncFrontend,
                            public browser_sync::UnrecoverableErrorHandler,
+                           public browser_sync::MigrationObserver,
                            public NotificationObserver {
  public:
   typedef ProfileSyncServiceObserver Observer;
@@ -352,7 +353,10 @@ class ProfileSyncService : public browser_sync::SyncFrontend,
   // UnrecoverableErrorHandler implementation.
   virtual void OnUnrecoverableError(
       const tracked_objects::Location& from_here,
-      const std::string& message);
+      const std::string& message) OVERRIDE;
+
+  // MigrationObserver implementation.
+  virtual void OnMigrationStateChange() OVERRIDE;
 
   // The functions below (until ActivateDataType()) should only be
   // called if sync_initialized() is true.
@@ -382,6 +386,10 @@ class ProfileSyncService : public browser_sync::SyncFrontend,
   // to server-initiated resynchronization.
   bool HasPendingBackendMigration() const;
 
+  // Returns the types that are currently pending migration.  Used by
+  // tests.
+  syncable::ModelTypeSet GetPendingMigrationTypesForTest() const;
+
   // Get the current routing information for all enabled model types.
   // If a model type is not enabled (that is, if the syncer should not
   // be trying to sync it), it is not in this map.