[Sync] Have configuration specify which datatypes are ready to sync

chrome/browser/sync/glue/sync_backend_host_impl.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/sync/glue/sync_backend_host_impl.h"
 
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/profiler/scoped_tracker.h"
 #include "chrome/browser/browser_process.h"
@@ skipping 306 matching lines @@
 }
 
 void SyncBackendHostImpl::UnregisterInvalidationIds() {
   if (invalidation_handler_registered_) {
     invalidator_->UpdateRegisteredInvalidationIds(
         this,
         syncer::ObjectIdSet());
   }
 }
 
-void SyncBackendHostImpl::ConfigureDataTypes(
+syncer::ModelTypeSet SyncBackendHostImpl::ConfigureDataTypes(
     syncer::ConfigureReason reason,
     const DataTypeConfigStateMap& config_state_map,
-    const base::Callback<void(syncer::ModelTypeSet,
-                              syncer::ModelTypeSet)>& ready_task,
+    const base::Callback<void(syncer::ModelTypeSet, syncer::ModelTypeSet)>&
+        ready_task,
     const base::Callback<void()>& retry_callback) {
   // Only one configure is allowed at a time.  This is guaranteed by our
   // callers.  The SyncBackendHostImpl requests one configure as the backend is
   // initializing and waits for it to complete.  After initialization, all
   // configurations will pass through the DataTypeManager, which is careful to
   // never send a new configure request until the current request succeeds.
 
   // The SyncBackendRegistrar's routing info will be updated by adding the
   // types_to_add to the list then removing types_to_remove.  Any types which
   // are not in either of those sets will remain untouched.
@@ skipping 96 matching lines @@
   //   touched.
   RequestConfigureSyncer(reason,
                          types_to_download,
                          types_to_purge,
                          fatal_types,
                          unapply_types,
                          inactive_types,
                          routing_info,
                          ready_task,
                          retry_callback);
+
+  DCHECK(syncer::Intersection(active_types, types_to_purge).Empty());
+  DCHECK(syncer::Intersection(active_types, fatal_types).Empty());
+  DCHECK(syncer::Intersection(active_types, unapply_types).Empty());
+  DCHECK(syncer::Intersection(active_types, inactive_types).Empty());
+  return syncer::Difference(active_types, types_to_download);
 }
 
 void SyncBackendHostImpl::EnableEncryptEverything() {
   registrar_->sync_thread()->message_loop()->PostTask(FROM_HERE,
      base::Bind(&SyncBackendHostCore::DoEnableEncryptEverything,
                 core_.get()));
 }
 
 void SyncBackendHostImpl::ActivateDataType(
     syncer::ModelType type, syncer::ModelSafeGroup group,
@@ skipping 431 matching lines @@
 
 base::MessageLoop* SyncBackendHostImpl::GetSyncLoopForTesting() {
   return registrar_->sync_thread()->message_loop();
 }
 
 }  // namespace browser_sync
 
 #undef SDVLOG
 
 #undef SLOG