Split a MetricsLogStore object out of MetricsLogManager.

components/ukm/ukm_service_unittest.cc

 // Copyright 2017 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.
 
 #include "components/ukm/ukm_service.h"
 
 #include <string>
 #include <utility>
 
 #include "base/test/test_simple_task_runner.h"
@@ skipping 31 matching lines @@
 
   Report GetPersistedReport() {
     EXPECT_GE(GetPersistedLogCount(), 1);
     metrics::PersistedLogs result_persisted_logs(
         base::MakeUnique<ukm::PersistedLogsMetricsImpl>(), &prefs_,
         prefs::kUkmPersistedLogs,
         3,     // log count limit
         1000,  // byte limit
         0);
 
-    result_persisted_logs.DeserializeLogs();
-    result_persisted_logs.StageLog();
+    result_persisted_logs.LoadPersistedUnsentLogs();
+    result_persisted_logs.StageNextLog();
 
     std::string uncompressed_log_data;
     EXPECT_TRUE(compression::GzipUncompress(result_persisted_logs.staged_log(),
                                             &uncompressed_log_data));
 
     Report report;
     EXPECT_TRUE(report.ParseFromString(uncompressed_log_data));
     return report;
   }
 
@@ skipping 118 matching lines @@
   // Includes a Source, so will persist.
   service.Flush();
   EXPECT_EQ(GetPersistedLogCount(), 1);
 
   // Current log has no Sources.
   service.Flush();
   EXPECT_EQ(GetPersistedLogCount(), 1);
 }
 
 }  // namespace ukm