Disallow JS execution on WebUI pages.

ios/web/public/test/web_view_interaction_test_util.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.
 
 #import "ios/web/public/test/web_view_interaction_test_util.h"
 
 #import "base/mac/bind_objc_block.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #import "base/test/ios/wait_util.h"
@@ skipping 124 matching lines @@
                         "  var element = document.getElementById('%s');"
                         "  if (element) {"
                         "    element%s;"
                         "    return true;"
                         "  }"
                         "  return false;"
                         "})();",
                        element_id.c_str(), js_action];
   __block bool did_complete = false;
   __block bool element_found = false;
-  [web_controller executeUserJavaScript:script
-                      completionHandler:^(id result, NSError*) {
-                        did_complete = true;
-                        element_found = [result boolValue];
-                      }];
+
+  // |executeUserJavaScript:completionHandler:| is no-op for app-specific URLs,
+  // so simulate a user gesture by calling TouchTracking method.
+  [web_controller touched:YES];
+  [web_controller executeJavaScript:script
+                  completionHandler:^(id result, NSError*) {
+                    did_complete = true;
+                    element_found = [result boolValue];
+                  }];
 
   testing::WaitUntilConditionOrTimeout(testing::kWaitForJSCompletionTimeout, ^{
     return did_complete;
   });
 
   return element_found;
 }
 
 bool TapWebViewElementWithId(web::WebState* web_state,
                              const std::string& element_id) {
   return RunActionOnWebViewElementWithId(web_state, element_id,
                                          ELEMENT_ACTION_CLICK);
 }
 
 bool FocusWebViewElementWithId(web::WebState* web_state,
                                const std::string& element_id) {
   return RunActionOnWebViewElementWithId(web_state, element_id,
                                          ELEMENT_ACTION_FOCUS);
 }
 
 bool SubmitWebViewFormWithId(web::WebState* web_state,
                              const std::string& form_id) {
   return RunActionOnWebViewElementWithId(web_state, form_id,
                                          ELEMENT_ACTION_SUBMIT);
 }
 
 }  // namespace test
 }  // namespace web