Add chrome://site-engagement WebUI.

chrome/browser/ui/webui/engagement/BUILD.gn

Index: chrome/browser/ui/webui/engagement/BUILD.gn
diff --git a/chrome/browser/ui/webui/omnibox/BUILD.gn b/chrome/browser/ui/webui/engagement/BUILD.gn
similarity index 76%
copy from chrome/browser/ui/webui/omnibox/BUILD.gn
copy to chrome/browser/ui/webui/engagement/BUILD.gn
index 21613cbd2e893c9584cdb8f9602e49a8c0aaa280..e565ebdb779cbe8fbb7743dbbd5a767b645604e4 100644
--- a/chrome/browser/ui/webui/omnibox/BUILD.gn
+++ b/chrome/browser/ui/webui/engagement/BUILD.gn
@@ -1,4 +1,4 @@
-# Copyright 2014 The Chromium Authors. All rights reserved.
+# Copyright 2015 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.
 
@@ -7,6 +7,6 @@ import("//third_party/mojo/src/mojo/public/tools/bindings/mojom.gni")
 # GYP version: chrome/chrome_web_ui_mojo_bindings.gyp:webui_mojo_bindings
 mojom("mojo_bindings") {
   sources = [
-    "omnibox.mojom",
+    "site_engagement.mojom",
   ]
 }