PVer4: Add UMA metrics for time taken to: load DB, do prefix check,

components/safe_browsing_db/v4_local_database_manager.h

Index: components/safe_browsing_db/v4_local_database_manager.h
diff --git a/components/safe_browsing_db/v4_local_database_manager.h b/components/safe_browsing_db/v4_local_database_manager.h
index a5bdef46ae48c68c2802c375f7d8703c4910e09b..b6955cb2eb47a9c930d9dce8ee1de25e9bf2f3d4 100644
--- a/components/safe_browsing_db/v4_local_database_manager.h
+++ b/components/safe_browsing_db/v4_local_database_manager.h
@@ -109,6 +109,10 @@ class V4LocalDatabaseManager : public SafeBrowsingDatabaseManager {
     // The threat verdict for the URL being checked.
     SBThreatType result_threat_type;
 
+    // When the check was sent to the SafeBrowsing service. Used to record the

[Nathan Parker, 2016/10/21 20:21:19]

I'm not clear on this description.  Is it the full-hash-check sent to the
"safebrowsing.google.com" service, or is the Check*() check?

Maybe full_hash_check_start? or network_start_time?

[vakh (use Gerrit instead), 2016/10/21 22:54:04]

Done.

+    // time it takes to get the uncached full hashes from the service.
+    base::TimeTicks start;
+
     // The SafeBrowsing lists to check hash prefixes in.
     StoresToCheck stores_to_check;