[Sync] Don't synchronously stop datatypes that encounter errors

The datatype logic may be operating unders assumptions that break when
the type is stopped from under it, possibly triggering crashes.

BUG=402595

Review URL: https://codereview.chromium.org/462863002

Cr-Commit-Position: refs/heads/master@{#288954}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@288954 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/sync/glue/frontend_data_type_controller.cc

@@ -153,9 +153,12 @@ void FrontendDataTypeController::OnSingleDataTypeUnrecoverableError(
   if (!start_callback_.is_null()) {
     syncer::SyncMergeResult local_merge_result(type());
     local_merge_result.set_error(error);
-    start_callback_.Run(RUNTIME_ERROR,
-                        local_merge_result,
-                        syncer::SyncMergeResult(type()));
+    base::MessageLoop::current()->PostTask(
+        FROM_HERE,
+        base::Bind(start_callback_,
+                   RUNTIME_ERROR,
+                   local_merge_result,
+                   syncer::SyncMergeResult(type())));
   }
 }
 

components/sync_driver/ui_data_type_controller.cc

@@ -331,9 +331,12 @@ void UIDataTypeController::OnSingleDataTypeUnrecoverableError(
   if (!start_callback_.is_null()) {
     syncer::SyncMergeResult local_merge_result(type());
     local_merge_result.set_error(error);
-    start_callback_.Run(RUNTIME_ERROR,
-                        local_merge_result,
-                        syncer::SyncMergeResult(type()));
+    base::MessageLoop::current()->PostTask(
+        FROM_HERE,
+        base::Bind(start_callback_,
+                   RUNTIME_ERROR,
+                   local_merge_result,
+                   syncer::SyncMergeResult(type())));
   }
 }