Mojo: Armed Watchers

ios/web/webui/web_ui_mojo_inttest.mm

 // Copyright 2016 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 <memory>
 
 #include "base/memory/ptr_util.h"
 #include "base/run_loop.h"
 #import "base/test/ios/wait_util.h"
+#include "base/threading/thread_task_runner_handle.h"
 #import "ios/web/public/navigation_manager.h"
 #include "ios/web/public/web_ui_ios_data_source.h"
 #include "ios/web/public/webui/web_ui_ios_controller.h"
 #include "ios/web/public/webui/web_ui_ios_controller_factory.h"
 #include "ios/web/test/grit/test_resources.h"
 #include "ios/web/test/mojo_test.mojom.h"
 #include "ios/web/test/test_url_constants.h"
 #import "ios/web/test/web_int_test.h"
 #import "ios/web/web_state/ui/crw_web_controller.h"
 #import "ios/web/web_state/web_state_impl.h"
@@ skipping 134 matching lines @@
 // |TestUIHandler| sucessfully receives "ack" message from WebUI page.
 TEST_F(WebUIMojoTest, MessageExchange) {
   web_state()->SetWebUsageEnabled(true);
   web_state()->GetView();  // WebState won't load URL without view.
   NavigationManager::WebLoadParams load_params(GURL(
       url::SchemeHostPort(kTestWebUIScheme, kTestWebUIURLHost, 0).Serialize()));
   web_state()->GetNavigationManager()->LoadURLWithParams(load_params);
 
   // Wait until |TestUIHandler| receives "ack" message from WebUI page.
   base::test::ios::WaitUntilCondition(^{
-    base::RunLoop().RunUntilIdle();
+    // Flush any pending tasks. Don't RunUntilIdle() because
+    // RunUntilIdle() is incompatible with mojo::SimpleWatcher's
+    // automatic arming behavior, which Mojo JS still depends upon.
+    //
+    // TODO(crbug.com/701875): Introduce the full watcher API to JS and get rid
+    // of this hack.
+    base::RunLoop loop;
+    base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
+                                                  loop.QuitClosure());
+    loop.Run();
     return test_ui_handler()->IsFinReceived();
   });
 }
 
 }  // namespace web