Add chrome://site-engagement WebUI.

chrome/browser/engagement/site_engagement_service.h

Index: chrome/browser/engagement/site_engagement_service.h
diff --git a/chrome/browser/engagement/site_engagement_service.h b/chrome/browser/engagement/site_engagement_service.h
index a85a47075f7b7983a6ddbb4fe556951d8f91b3f5..9590cbd878b8903567e3923ffacb1a127a3b890b 100644
--- a/chrome/browser/engagement/site_engagement_service.h
+++ b/chrome/browser/engagement/site_engagement_service.h
@@ -5,6 +5,8 @@
 #ifndef CHROME_BROWSER_ENGAGEMENT_SITE_ENGAGEMENT_SERVICE_H_
 #define CHROME_BROWSER_ENGAGEMENT_SITE_ENGAGEMENT_SERVICE_H_
 
+#include <map>
+
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/time/default_clock.h"
@@ -118,6 +120,9 @@ class SiteEngagementService : public KeyedService,
   explicit SiteEngagementService(Profile* profile);
   ~SiteEngagementService() override;
 
+  // Returns a map of all stored origins and their engagement scores.
+  std::map<GURL, int> GetScoreMap();

[raymes, 2015/09/14 03:06:11]

Score() returns a double, should this be a double?

[calamity, 2015/09/15 04:38:49]

GetScore() returns an int. I believe the intention is to keep the external
representation fairly coarse-grained.

[raymes, 2015/09/15 07:23:01]

Ahh right, that makes sense. Sorry I was looking at the wrong function!

+
   // Update the karma score of the origin matching |url| for user navigation.
   void HandleNavigation(const GURL& url, ui::PageTransition transition_type);