Add a return value to TapWebViewElementWithId

ios/web/public/test/web_view_interaction_test_util.h

 // 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.
 
 #import "ios/web/public/web_state/web_state.h"
 
 #include <string>
 
 namespace web {
 namespace test {
 
-// Attempts to tap the element with |element_id| in the passed in |web_state|
-// using a JavaScript click() event.
-void TapWebViewElementWithId(web::WebState* web_state,
+// Returns whether the element with |element_id| in the passed |web_state| has
+// been tapped using a JavaScript click() event.
+bool TapWebViewElementWithId(web::WebState* web_state,
                              const std::string& element_id);
 
 }  // namespace test
-}  // namespace web
+}  // namespace web