[Sync::USS] Set the model type state upon handling remote updates

Bug: 516866
Change-Id: I2a460de83529e88058054d2407da6a6d8f6e9357
Reviewed-on: https://chromium-review.googlesource.com/1169053
Commit-Queue: Mohamed Amir Yosef <mamir@chromium.org>
Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#581943}

components/sync_bookmarks/bookmark_model_type_processor.cc

@@ -153,13 +153,13 @@ void BookmarkModelTypeProcessor::OnUpdateReceived(
     NudgeForCommitIfNeeded();
     return;
   }
-  // TODO(crbug.com/516866): Set the model type state.
-
   ScopedRemoteUpdateBookmarks update_bookmarks(
       bookmark_model_, bookmark_undo_service_, bookmark_model_observer_.get());
   BookmarkRemoteUpdatesHandler updates_handler(bookmark_model_,
                                                bookmark_tracker_.get());
   updates_handler.Process(updates);
+  bookmark_tracker_->set_model_type_state(
+      std::make_unique<sync_pb::ModelTypeState>(model_type_state));
   // Schedule save just in case one is needed.
   schedule_save_closure_.Run();
 }

components/sync_bookmarks/bookmark_model_type_processor_unittest.cc

@@ -339,6 +339,34 @@ TEST_F(BookmarkModelTypeProcessorTest, ShouldDecodeEncodedSyncMetadata) {
   AssertState(&new_processor, bookmarks);
 }
 
+// Verifies that the model type state stored in the tracker gets
+// updated upon handling remote updates by assigning a new encryption
+// key name.
+TEST_F(BookmarkModelTypeProcessorTest,
+       ShouldUpdateModelTypeStateUponHandlingRemoteUpdates) {
+  // Initialize the process to make sure the tracker has been created.
+  InitWithSyncedBookmarks({}, processor());
+  const SyncedBookmarkTracker* tracker = processor()->GetTrackerForTest();
+  // The encryption key name should be empty.
+  ASSERT_TRUE(tracker->model_type_state().encryption_key_name().empty());
+
+  // Build a model type state with an encryption key name.
+  const std::string kEncryptionKeyName = "new_encryption_key_name";
+  sync_pb::ModelTypeState model_type_state(CreateDummyModelTypeState());
+  model_type_state.set_encryption_key_name(kEncryptionKeyName);
+
+  EXPECT_CALL(*schedule_save_closure(), Run());
+  // Push empty updates list to the processor together with the updated model
+  // type state.
+  processor()->OnUpdateReceived(model_type_state,
+                                syncer::UpdateResponseDataList());
+
+  // The model type state inside the tracker should have been updated, and
+  // carries the new encryption key name.
+  EXPECT_THAT(tracker->model_type_state().encryption_key_name(),
+              Eq(kEncryptionKeyName));
+}
+
 }  // namespace
 
 }  // namespace sync_bookmarks