Add chrome://site-engagement WebUI.

chrome/browser/ui/webui/chrome_web_ui_controller_factory.cc

Index: chrome/browser/ui/webui/chrome_web_ui_controller_factory.cc
diff --git a/chrome/browser/ui/webui/chrome_web_ui_controller_factory.cc b/chrome/browser/ui/webui/chrome_web_ui_controller_factory.cc
index f1092afface7e2d9d9a8a9b21de00e5866a086dd..af088e104c9da29265d8d794d59e1b84077aae58 100644
--- a/chrome/browser/ui/webui/chrome_web_ui_controller_factory.cc
+++ b/chrome/browser/ui/webui/chrome_web_ui_controller_factory.cc
@@ -13,6 +13,7 @@
 #include "base/thread_task_runner_handle.h"
 #include "chrome/browser/about_flags.h"
 #include "chrome/browser/dom_distiller/dom_distiller_service_factory.h"
+#include "chrome/browser/engagement/site_engagement_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/ui/webui/about_ui.h"
@@ -23,6 +24,7 @@
 #include "chrome/browser/ui/webui/device_log_ui.h"
 #include "chrome/browser/ui/webui/domain_reliability_internals_ui.h"
 #include "chrome/browser/ui/webui/downloads_ui.h"
+#include "chrome/browser/ui/webui/engagement/site_engagement_ui.h"
 #include "chrome/browser/ui/webui/flags_ui.h"
 #include "chrome/browser/ui/webui/flash_ui.h"
 #include "chrome/browser/ui/webui/gcm_internals_ui.h"
@@ -584,6 +586,11 @@ WebUIFactoryFunction GetWebUIFactoryFunction(WebUI* web_ui,
     return &NewWebUI<dom_distiller::DomDistillerUi>;
   }
 
+  if (SiteEngagementService::IsEnabled() &&
+      url.host() == chrome::kChromeUISiteEngagementHost) {
+    return &NewWebUI<SiteEngagementUI>;
+  }
+
   return NULL;
 }