Sync tasks with GTask list but no GTask ID.

When synchronising up a Google Tasks list, find any
tasks which were not successfully pushed on create, and
force them to exist remotely. Otherwise, we will wipe
them locally as we assume the user has moved or deleted
the task remotely.

astrid/src/main/java/com/todoroo/astrid/gtasks/sync/GtasksSyncV2Provider.java

@@ -168,8 +168,12 @@ public class GtasksSyncV2Provider extends SyncV2Provider {
         TodorooCursor<Task> queued = taskService.query(Query.select(Task.PROPERTIES).
                 join(Join.left(Metadata.TABLE, Criterion.and(MetadataCriteria.withKey(GtasksMetadata.METADATA_KEY), Task.ID.eq(Metadata.TASK)))).where(
                         Criterion.or(Task.MODIFICATION_DATE.gt(GtasksMetadata.LAST_SYNC),
-                                Criterion.and(Task.USER_ID.neq(Task.USER_ID_SELF), GtasksMetadata.ID.isNotNull()),
+                                Criterion.and(Task.USER_ID.neq(Task.USER_ID_SELF), GtasksMetadata.ID.isNotNull()), // XXX: Shouldn't this neq("")?
                                       Metadata.KEY.isNull())));
+        pushTasks(queued, invoker, callback);
+    }
+
+    private synchronized void pushTasks(TodorooCursor<Task> queued, GtasksInvoker invoker, SyncResultCallback callback) {
         callback.incrementMax(queued.getCount() * 10);
         try {
             Task task = new Task();
@@ -248,6 +252,21 @@ public class GtasksSyncV2Provider extends SyncV2Provider {
         } else {
             lastSyncDate = 0;
         }
+
+        /**
+         * Find tasks which have been associated with the list internally, but have not yet been
+         * pushed to Google Tasks (and so haven't yet got a valid ID).
+         */
+        Criterion not_pushed_tasks = Criterion.and(
+                Metadata.KEY.eq(GtasksMetadata.METADATA_KEY),
+                GtasksMetadata.LIST_ID.eq(listId),
+                GtasksMetadata.ID.eq("")
+        );
+        TodorooCursor<Task> qs = taskService.query(Query.select(Task.PROPERTIES).
+                join(Join.left(Metadata.TABLE, Criterion.and(MetadataCriteria.withKey(GtasksMetadata.METADATA_KEY), Task.ID.eq(Metadata.TASK)))).where(not_pushed_tasks)
+        );
+        pushTasks(qs, invoker, callback);
+
         boolean includeDeletedAndHidden = lastSyncDate != 0;
         try {
             Tasks taskList = invoker.getAllGtasksFromListId(listId, includeDeletedAndHidden,