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

components/safe_browsing_db/v4_local_database_manager.h

 // Copyright 2016 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.
 
 #ifndef COMPONENTS_SAFE_BROWSING_DB_V4_LOCAL_DATABASE_MANAGER_H_
 #define COMPONENTS_SAFE_BROWSING_DB_V4_LOCAL_DATABASE_MANAGER_H_
 
 // A class that provides the interface between the SafeBrowsing protocol manager
 // and database that holds the downloaded updates.
 
@@ skipping 91 matching lines @@
     // The SafeBrowsing client that's waiting for the safe/unsafe verdict.
     Client* client;
 
     // Determines which funtion from the |client| needs to be called once we
     // know whether the URL in |url| is safe or unsafe.
     ClientCallbackType client_callback_type;
 
     // 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;
 
     // The URL that is being checked for being unsafe.
     GURL url;
 
     // The metadata associated with the full hash of the severest match found
     // for that URL.
     ThreatMetadata url_metadata;
   };
@@ skipping 116 matching lines @@
 
   base::WeakPtrFactory<V4LocalDatabaseManager> weak_factory_;
 
   friend class base::RefCountedThreadSafe<V4LocalDatabaseManager>;
   DISALLOW_COPY_AND_ASSIGN(V4LocalDatabaseManager);
 };  // class V4LocalDatabaseManager
 
 }  // namespace safe_browsing
 
 #endif  // COMPONENTS_SAFE_BROWSING_DB_V4_LOCAL_DATABASE_MANAGER_H_