Add chrome://site-engagement WebUI.

chrome/browser/ui/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/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 
 gypi_values = exec_script("//build/gypi_to_gn.py",
                           [ rebase_path("../../chrome_browser_ui.gypi") ],
@@ skipping 69 matching lines @@
   if (!is_ios) {
     sources += rebase_path(gypi_values.chrome_browser_ui_non_ios_sources,
                            ".",
                            "//chrome")
     sources += rebase_path(gypi_values.chrome_browser_ui_toolbar_model_sources,
                            ".",
                            "//chrome")
     deps += [
       "//chrome/browser/devtools",
       "//chrome/browser/ui/views",
+      "//chrome/browser/ui/webui/engagement:mojo_bindings",
       "//chrome/browser/ui/webui/omnibox:mojo_bindings",
       "//chrome/common/net",
       "//chrome/installer/util",
       "//components/autofill/content/browser:risk_proto",
       "//components/power",
       "//components/suggestions/proto",
       "//components/url_formatter",
       "//device/nfc",
       "//media",
       "//net:net_with_v8",
@@ skipping 430 matching lines @@
     "//chrome/browser",
     "//content/public/browser",
     "//content/public/common",
     "//content/test:test_support",
     "//net:test_support",
     "//skia",
     "//testing/gtest",
     "//ui/base",
   ]
 }