Add chrome://site-engagement WebUI.

chrome/browser/ui/webui/engagement/site_engagement_ui.h

Index: chrome/browser/ui/webui/engagement/site_engagement_ui.h
diff --git a/chrome/browser/ui/webui/engagement/site_engagement_ui.h b/chrome/browser/ui/webui/engagement/site_engagement_ui.h
new file mode 100644
index 0000000000000000000000000000000000000000..678362a06c0668ddbda2289358b9af9b2b934641
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+++ b/chrome/browser/ui/webui/engagement/site_engagement_ui.h
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+// 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.
+
+#ifndef CHROME_BROWSER_UI_WEBUI_ENGAGEMENT_SITE_ENGAGEMENT_UI_H_
+#define CHROME_BROWSER_UI_WEBUI_ENGAGEMENT_SITE_ENGAGEMENT_UI_H_
+
+#include "base/macros.h"
+#include "chrome/browser/ui/webui/engagement/site_engagement.mojom.h"
+#include "chrome/browser/ui/webui/mojo_web_ui_controller.h"
+
+// The UI for chrome://site-engagement/.
+class SiteEngagementUI : public MojoWebUIController<SiteEngagementUIHandler> {
+ public:
+  explicit SiteEngagementUI(content::WebUI* web_ui);
+  ~SiteEngagementUI() override;
+
+ private:
+  // MojoWebUIController overrides:
+  void BindUIHandler(
+      mojo::InterfaceRequest<SiteEngagementUIHandler> request) override;
+
+  DISALLOW_COPY_AND_ASSIGN(SiteEngagementUI);
+};
+
+#endif  // CHROME_BROWSER_UI_WEBUI_ENGAGEMENT_SITE_ENGAGEMENT_UI_H_