Add chrome://site-engagement WebUI.

chrome/browser/ui/webui/engagement/site_engagement_ui_handler.cc

+// 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.
+
+#include "chrome/browser/ui/webui/engagement/site_engagement_ui_handler.h"
+
+#include "chrome/browser/engagement/site_engagement_service.h"
+#include "mojo/common/common_type_converters.h"
+#include "url/gurl.h"
+
+SiteEngagementUIHandler::SiteEngagementUIHandler(
+    Profile* profile,
+    mojo::InterfaceRequest<SiteEngagementUIHandlerMojo> request)
+    : profile_(profile), binding_(this, request.Pass()) {}
+
+SiteEngagementUIHandler::~SiteEngagementUIHandler() {}
+
+void SiteEngagementUIHandler::GetSiteEngagementInfo(
+    const GetSiteEngagementInfoCallback& callback) {
+  mojo::Array<SiteEngagementInfoPtr> engagement_info;

[Sam McNally, 2015/09/08 08:25:47]

You probably need to resize this to 0. Otherwise, it'll be null if there are no
sites and the validation will fail.

[calamity, 2015/09/10 06:57:33]

Done.

+
+  SiteEngagementService* service = SiteEngagementService::Get(profile_);
+  DCHECK(service);
+
+  for (auto info : service->GetScoreMap()) {
+    SiteEngagementInfoPtr origin_info(SiteEngagementInfo::New());
+    origin_info->origin = mojo::String::From(info.first.spec());

[Sam McNally, 2015/09/08 08:25:47]

#include "mojo/common/url_type_converters.h" and convert directly from
info.first.

[calamity, 2015/09/10 06:57:33]

Done.

+    origin_info->score = info.second;
+    engagement_info.push_back(origin_info.Pass());
+  }
+
+  callback.Run(engagement_info.Pass());
+}