Delete GenericChangeProcessor synchronously when possible.

components/sync_driver/shared_change_processor.cc

Index: components/sync_driver/shared_change_processor.cc
diff --git a/components/sync_driver/shared_change_processor.cc b/components/sync_driver/shared_change_processor.cc
index c1cf407e74647f25db86a9309fccb236b4bfeeb6..ce494303414c8cede1730a9eb0b7b7b7f8f32c8c 100644
--- a/components/sync_driver/shared_change_processor.cc
+++ b/components/sync_driver/shared_change_processor.cc
@@ -24,21 +24,20 @@ SharedChangeProcessor::SharedChangeProcessor()
 
 SharedChangeProcessor::~SharedChangeProcessor() {
   // We can either be deleted when the DTC is destroyed (on UI
-  // thread), or when the syncer::SyncableService stop's syncing (datatype
+  // thread), or when the syncer::SyncableService stops syncing (datatype
   // thread).  |generic_change_processor_|, if non-NULL, must be
   // deleted on |backend_loop_|.
-  if (frontend_loop_->BelongsToCurrentThread()) {
-    if (backend_loop_.get()) {
+  if (backend_loop_.get()) {
+    if (backend_loop_->BelongsToCurrentThread()) {
+      delete generic_change_processor_;
+    } else {
+      DCHECK(frontend_loop_->BelongsToCurrentThread());
       if (!backend_loop_->DeleteSoon(FROM_HERE, generic_change_processor_)) {
         NOTREACHED();
       }
-    } else {
-      DCHECK(!generic_change_processor_);
     }
   } else {
-    DCHECK(backend_loop_.get());
-    DCHECK(backend_loop_->BelongsToCurrentThread());
-    delete generic_change_processor_;
+    DCHECK(!generic_change_processor_);
   }
 }