Add chrome://site-engagement WebUI.

chrome/browser/browser_resources.grd

 <?xml version="1.0" encoding="UTF-8"?>
 <grit latest_public_release="0" current_release="1">
   <outputs>
     <output filename="grit/browser_resources.h" type="rc_header">
       <emit emit_type='prepend'></emit>
     </output>
     <output filename="browser_resources.pak" type="data_package" />
   </outputs>
   <release seq="1">
     <structures>
@@ skipping 213 matching lines @@
       <include name="IDR_MOST_VISITED_THUMBNAIL_CSS" file="resources\local_ntp\most_visited_thumbnail.css" type="BINDATA" />
       <include name="IDR_MOST_VISITED_THUMBNAIL_JS" file="resources\local_ntp\most_visited_thumbnail.js" type="BINDATA" />
       <include name="IDR_MOST_VISITED_SINGLE_HTML" file="resources\local_ntp\most_visited_single.html" type="BINDATA" />
       <include name="IDR_MOST_VISITED_SINGLE_CSS" file="resources\local_ntp\most_visited_single.css" type="BINDATA" />
       <include name="IDR_MOST_VISITED_SINGLE_JS" file="resources\local_ntp\most_visited_single.js" type="BINDATA" />
       <include name="IDR_MOST_VISITED_UTIL_JS" file="resources\local_ntp\most_visited_util.js" type="BINDATA" flattenhtml="true" />
       <include name="IDR_MOST_VISITED_WINDOW_DISPOSITION_UTIL_JS" file="resources\local_ntp\window_disposition_util.js" type="BINDATA" />
       <include name="IDR_OMNIBOX_HTML" file="resources\omnibox\omnibox.html" flattenhtml="true" allowexternalscript="true" type="BINDATA" />
       <include name="IDR_OMNIBOX_CSS" file="resources\omnibox\omnibox.css" type="BINDATA" />
       <include name="IDR_OMNIBOX_JS" file="resources\omnibox\omnibox.js" type="BINDATA" />
-      <include name="IDR_OMNIBOX_MOJO_JS" file="${omnibox_mojom_file}" use_base_dir="false" type="BINDATA"/>
+      <include name="IDR_OMNIBOX_MOJO_JS" file="${root_gen_dir}\chrome\browser\ui\webui\omnibox\omnibox.mojom.js" use_base_dir="false" type="BINDATA"/>
       <if expr="enable_plugins">
         <include name="IDR_PLUGINS_HTML" file="resources\plugins.html" flattenhtml="true" allowexternalscript="true" type="BINDATA" />
         <include name="IDR_PLUGINS_JS" file="resources\plugins.js" type="BINDATA" />
       </if>
       <include name="IDR_COMPONENTS_HTML" file="resources\components.html" flattenhtml="true" allowexternalscript="true" type="BINDATA" />
       <include name="IDR_COMPONENTS_JS" file="resources\components.js" type="BINDATA" />
       <if expr="enable_plugins">
         <include name="IDR_PDF_MANIFEST" file="resources\pdf\manifest.json" type="BINDATA" />
       </if>
       <if expr="is_win">
@@ skipping 39 matching lines @@
                  file="resources\print_preview\images\mobile_shared.png" type="BINDATA" />
       </if>
       <include name="IDR_PROFILER_HTML" file="resources\profiler\profiler.html" flattenhtml="true" allowexternalscript="true" type="BINDATA" />
       <include name="IDR_PROFILER_JS" file="resources\profiler\profiler.js" flattenhtml="true" type="BINDATA" />
       <if expr="enable_settings_app">
         <include name="IDR_SETTINGS_APP_MANIFEST" file="resources\settings_app\manifest.json" type="BINDATA" />
       </if>
       <if expr="enable_google_now">
         <include name="IDR_GOOGLE_NOW_MANIFEST" file="resources\google_now\manifest.json" type="BINDATA" />
       </if>
+      <include name="IDR_SITE_ENGAGEMENT_HTML" file="resources\engagement\site_engagement.html" flattenhtml="true" type="BINDATA" />
+      <include name="IDR_SITE_ENGAGEMENT_JS" file="resources\engagement\site_engagement.js" flattenhtml="true" type="BINDATA" />
+      <include name="IDR_SITE_ENGAGEMENT_MOJO_JS" file="${root_gen_dir}\chrome\browser\ui\webui\engagement\site_engagement.mojom.js" use_base_dir="false" type="BINDATA"/>
+      <include name="IDR_SITE_ENGAGEMENT_ENGAGEMENT_TABLE_CSS" file="resources\engagement\engagement_table.css" type="BINDATA" />
+      <include name="IDR_SITE_ENGAGEMENT_ENGAGEMENT_TABLE_HTML" file="resources\engagement\engagement_table.html" type="BINDATA" />
+      <include name="IDR_SITE_ENGAGEMENT_ENGAGEMENT_TABLE_JS" file="resources\engagement\engagement_table.js" type="BINDATA" />
       <include name="IDR_UBER_HTML" file="resources\uber\uber.html" flattenhtml="true" type="BINDATA" />
       <include name="IDR_UBER_JS" file="resources\uber\uber.js" type="BINDATA" />
       <include name="IDR_UBER_FRAME_HTML" file="resources\uber\uber_frame.html" flattenhtml="true" type="BINDATA" />
       <include name="IDR_UBER_FRAME_JS" file="resources\uber\uber_frame.js" flattenhtml="true" type="BINDATA" />
       <include name="IDR_UBER_UTILS_JS" file="resources\uber\uber_utils.js" type="BINDATA" />
       <include name="IDR_USER_ACTIONS_HTML" file="resources\user_actions\user_actions.html" flattenhtml="true" allowexternalscript="true" type="BINDATA" />
       <include name="IDR_USER_ACTIONS_CSS" file="resources\user_actions\user_actions.css" type="BINDATA" />
       <include name="IDR_USER_ACTIONS_JS" file="resources\user_actions\user_actions.js" type="BINDATA" />
       <if expr="enable_webrtc">
         <include name="IDR_WEBRTC_LOGS_HTML" file="resources\media\webrtc_logs.html" flattenhtml="true" allowexternalscript="true" type="BINDATA" />
@@ skipping 146 matching lines @@
         </if>
         <include name="IDR_BRAILLE_MANIFEST" file="resources\chromeos\braille_ime\manifest.json" type="BINDATA" />
       </if>
       <include name="IDR_WHISPERNET_PROXY_MANIFEST" file="resources\whispernet_proxy\manifest.json" type="BINDATA" />
       <if expr="enable_media_router">
         <part file="media_router_resources.grdp" />
       </if>
     </includes>
   </release>
 </grit>