Fix event warning crash when a listener is removed while dispatching event

components/test_runner/layout_test_runtime_flags.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.
 
 #ifndef COMPONENTS_TEST_RUNNER_LAYOUT_TEST_RUNTIME_FLAGS_H_
 #define COMPONENTS_TEST_RUNNER_LAYOUT_TEST_RUNTIME_FLAGS_H_
 
 #include <string>
 
 #include "base/logging.h"
@@ skipping 134 matching lines @@
   // If true, content_shell will dump the default navigation policy passed to
   // WebFrameClient::decidePolicyForNavigation.
   DEFINE_BOOL_LAYOUT_TEST_RUNTIME_FLAG(dump_navigation_policy)
 
   // If true, output a message when the page title is changed.
   DEFINE_BOOL_LAYOUT_TEST_RUNTIME_FLAG(dump_title_changes)
 
   // If true, the test_shell will print out the icon change notifications.
   DEFINE_BOOL_LAYOUT_TEST_RUNTIME_FLAG(dump_icon_changes)
 
+  // If true, the console messages produced by the page will
+  // be part of test output.
+  DEFINE_BOOL_LAYOUT_TEST_RUNTIME_FLAG(dump_console_messages)
+
   // Desired return value of WebFrameClient::runModalBeforeUnloadDialog.
   DEFINE_BOOL_LAYOUT_TEST_RUNTIME_FLAG(
       stay_on_page_after_handling_before_unload)
 
   // Indicates if the test already tracks a top loading frame (in any of the
   // renderer processes).  This flag is trying to prevent different renderer
   // processes from tracking different top loading frames (i.e. main frame in
   // one renderer and an OOPIF in another renderer).
   DEFINE_BOOL_LAYOUT_TEST_RUNTIME_FLAG(have_top_loading_frame)
 
@@ skipping 12 matching lines @@
 
  private:
   TrackedDictionary dict_;
 
   DISALLOW_COPY_AND_ASSIGN(LayoutTestRuntimeFlags);
 };
 
 }  // namespace test_runner
 
 #endif  // COMPONENTS_TEST_RUNNER_LAYOUT_TEST_RUNTIME_FLAGS_H_