Add SiteEngagementService::GetAllDetails(), to return detailed scores.

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 35c005d1af69eefa392635567bbcf358f053b12c..e5879e8a1011cf571cfe341f2887f0feb625146c 100644
--- a/chrome/browser/engagement/site_engagement_service.h
+++ b/chrome/browser/engagement/site_engagement_service.h
@@ -15,6 +15,7 @@
 #include "base/observer_list.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
+#include "chrome/browser/engagement/site_engagement_details.mojom.h"
 #include "chrome/browser/engagement/site_engagement_metrics.h"
 #include "chrome/browser/engagement/site_engagement_observer.h"
 #include "components/history/core/browser/history_service_observer.h"
@@ -116,7 +117,12 @@ class SiteEngagementService : public KeyedService,
   // Returns the engagement level of |url|.
   blink::mojom::EngagementLevel GetEngagementLevel(const GURL& url) const;
 
+  // Returns SiteEngagementDetails structures describing the score details for
+  // all stored origins.
+  std::vector<mojom::SiteEngagementDetails> GetScoreDetails() const;
+
   // Returns a map of all stored origins and their engagement scores.
+  // TODO(wez): Remove this!

[Wez, 2017/04/10 03:45:28]

AFAICT the only callers of this are:
1. to calculate the total engagement score across all sites.
2. to get data to pass to record site engagement metrics.
3. for important sites to use to grab scores.

Since #3 will be switched to use GetAllDetails() anyway, is it acceptable to
switch the other callers to use that as well?

The argument against doing so would be that GetAllDetails() is considerably more
expensive, since it allocates internal buffers for a GURL for each entry.

How often do we expect #1 and #2 to be called?

   std::map<GURL, double> GetScoreMap() const;
 
   // Update the engagement score of |url| for a notification interaction.
@@ -143,6 +149,9 @@ class SiteEngagementService : public KeyedService,
   void HelperCreated(SiteEngagementService::Helper* helper);
   void HelperDeleted(SiteEngagementService::Helper* helper);
 
+  // Returns the site engagement details for the specified |url|.
+  mojom::SiteEngagementDetails GetScoreDetails(const GURL& url) const;
+
   // Overridden from SiteEngagementScoreProvider.
   double GetScore(const GURL& url) const override;
   double GetTotalEngagementPoints() const override;