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

components/safe_browsing_db/v4_database.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_DATABASE_H_
 #define COMPONENTS_SAFE_BROWSING_DB_V4_DATABASE_H_
 
 #include "base/callback.h"
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
@@ skipping 146 matching lines @@
     factory_ = factory;
   }
 
   // Factory method to create a V4Database. When the database creation is
   // complete, it calls the NewDatabaseReadyCallback on |callback_task_runner|.
   static void CreateOnTaskRunner(
       const scoped_refptr<base::SequencedTaskRunner>& db_task_runner,
       const base::FilePath& base_path,
       const ListInfos& list_infos,
       const scoped_refptr<base::SingleThreadTaskRunner>& callback_task_runner,
-      NewDatabaseReadyCallback callback);
+      NewDatabaseReadyCallback callback,
+      const base::TimeTicks before);

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

How about "create_start_time?" "before" is nonobvious.

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

Done.

 
   // Callback called when a new store has been created and is ready to be used.
   // This method updates the store_map_ to point to the new store, which causes
   // the old store to get deleted.
   void UpdatedStoreReady(ListIdentifier identifier,
                          std::unique_ptr<V4Store> store);
 
   // See |VerifyChecksum|.
   void VerifyChecksumOnTaskRunner(
       const scoped_refptr<base::SingleThreadTaskRunner>& callback_task_runner,
@@ skipping 14 matching lines @@
   // that needed updating and is ready for the next update. It should only be
   // accessed on the IO thread.
   int pending_store_updates_;
 
   DISALLOW_COPY_AND_ASSIGN(V4Database);
 };
 
 }  // namespace safe_browsing
 
 #endif  // COMPONENTS_SAFE_BROWSING_DB_V4_DATABASE_H_