Remove the allow-displaying-mixed-content setting from Blink.

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 91 matching lines @@
   DEFINE_BOOL_LAYOUT_TEST_RUNTIME_FLAG(dump_drag_image)
 
   // Contents of Accept-Language HTTP header requested by the test.
   DEFINE_STRING_LAYOUT_TEST_RUNTIME_FLAG(accept_languages)
 
   // Flags influencing behavior of MockContentSettingsClient.
   DEFINE_BOOL_LAYOUT_TEST_RUNTIME_FLAG(images_allowed)
   DEFINE_BOOL_LAYOUT_TEST_RUNTIME_FLAG(scripts_allowed)
   DEFINE_BOOL_LAYOUT_TEST_RUNTIME_FLAG(storage_allowed)
   DEFINE_BOOL_LAYOUT_TEST_RUNTIME_FLAG(plugins_allowed)
-  DEFINE_BOOL_LAYOUT_TEST_RUNTIME_FLAG(displaying_insecure_content_allowed)
   DEFINE_BOOL_LAYOUT_TEST_RUNTIME_FLAG(running_insecure_content_allowed)
   DEFINE_BOOL_LAYOUT_TEST_RUNTIME_FLAG(
       dump_web_content_settings_client_callbacks)
   DEFINE_BOOL_LAYOUT_TEST_RUNTIME_FLAG(autoplay_allowed)
 
   // If true, the test_shell will write a descriptive line for each editing
   // command.
   DEFINE_BOOL_LAYOUT_TEST_RUNTIME_FLAG(dump_editting_callbacks)
 
   // If true, the test_shell will output a descriptive line for each frame
@@ skipping 72 matching lines @@
 
  private:
   TrackedDictionary dict_;
 
   DISALLOW_COPY_AND_ASSIGN(LayoutTestRuntimeFlags);
 };
 
 }  // namespace test_runner
 
 #endif  // COMPONENTS_TEST_RUNNER_LAYOUT_TEST_RUNTIME_FLAGS_H_