Add the ability to override WebContentsBindingSet binders for testing

content/test/BUILD.gn

 # Copyright 2014 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("//build/config/chrome_build.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
@@ skipping 643 matching lines @@
     "../browser/top_document_isolation_browsertest.cc",
     "../browser/tracing/background_tracing_manager_browsertest.cc",
     "../browser/tracing/memory_tracing_browsertest.cc",
     "../browser/tracing/tracing_controller_browsertest.cc",
     "../browser/utility_process_host_impl_browsertest.cc",
     "../browser/utility_process_mojo_client_browsertest.cc",
     "../browser/wake_lock/wake_lock_browsertest.cc",
     "../browser/web_contents/opened_by_dom_browsertest.cc",
     "../browser/web_contents/web_contents_impl_browsertest.cc",
     "../browser/web_contents/web_contents_view_aura_browsertest.cc",
+    "../browser/web_contents_binding_set_browsertest.cc",
     "../browser/webkit_browsertest.cc",
     "../browser/webui/web_ui_mojo_browsertest.cc",
     "../browser/zoom_browsertest.cc",
     "../child/site_isolation_stats_gatherer_browsertest.cc",
     "../renderer/accessibility/render_accessibility_impl_browsertest.cc",
     "../renderer/blink_platform_audio_hardware_browsertest.cc",
     "../renderer/gin_browsertest.cc",
     "../renderer/media/renderer_webmediaplayer_delegate_browsertest.cc",
     "../renderer/mouse_lock_dispatcher_browsertest.cc",
     "../renderer/render_frame_impl_browsertest.cc",
@@ skipping 1159 matching lines @@
   if (is_android) {
     deps += [ "//testing/android/native_test:native_test_native_code" ]
   }
 }
 
 group("fuzzers") {
   deps = [
     "//content/test/fuzzer",
   ]
 }