Add experiment to exercise AffiliationService with dummy data, plus add related UMA histograms.

components/password_manager/core/browser/affiliation_backend.h

Index: components/password_manager/core/browser/affiliation_backend.h
diff --git a/components/password_manager/core/browser/affiliation_backend.h b/components/password_manager/core/browser/affiliation_backend.h
index 88dce8d6140201648236445b6115ff95353fa240..334dd264b3591a951541852256f33d3ebe3b03f5 100644
--- a/components/password_manager/core/browser/affiliation_backend.h
+++ b/components/password_manager/core/browser/affiliation_backend.h
@@ -110,6 +110,10 @@ class AffiliationBackend : public FacetManagerHost,
   // Returns the number of in-memory FacetManagers. Used only for testing.
   size_t facet_manager_count_for_testing() { return facet_managers_.size(); }
 
+  // Reports the |requested_facet_uri_count| in a single fetch; and the elapsed
+  // time before the first fetch, and in-between subsequent fetches.
+  void ReportStatistics(size_t requested_facet_uri_count);
+
   // To be called after Initialize() to use |throttler| instead of the default
   // one. Used only for testing.
   void SetThrottlerForTesting(scoped_ptr<AffiliationFetchThrottler> throttler);
@@ -127,6 +131,9 @@ class AffiliationBackend : public FacetManagerHost,
   scoped_ptr<AffiliationFetcher> fetcher_;
   scoped_ptr<AffiliationFetchThrottler> throttler_;
 
+  base::Time construction_time_;
+  base::Time last_request_time_;
+
   // Contains a FacetManager for each facet URI that need ongoing attention. To
   // save memory, managers are discarded as soon as they become redundant.
   base::ScopedPtrHashMap<FacetURI, FacetManager> facet_managers_;