Added support for 'spare' file that can be used at startup.

chrome/browser/metrics/chrome_metrics_service_client.cc

 // Copyright 2014 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 "chrome/browser/metrics/chrome_metrics_service_client.h"
 
 #include <stddef.h>
 
 #include <set>
 #include <utility>
@@ skipping 163 matching lines @@
 // Constructs the name of a persistent metrics file from a directory and metrics
 // name, and either registers that file as associated with a previous run if
 // metrics reporting is enabled, or deletes it if not.
 void RegisterOrRemovePreviousRunMetricsFile(
     bool metrics_reporting_enabled,
     const base::FilePath& dir,
     base::StringPiece metrics_name,
     scoped_refptr<base::TaskRunner> task_runner,
     metrics::FileMetricsProvider* file_metrics_provider) {
   base::FilePath metrics_file;
-  base::GlobalHistogramAllocator::ConstructFilePaths(dir, metrics_name,
-                                                     &metrics_file, nullptr);
+  base::GlobalHistogramAllocator::ConstructFilePaths(
+      dir, metrics_name, &metrics_file, nullptr, nullptr);
 
   if (metrics_reporting_enabled) {
     // Enable reading any existing saved metrics.
     file_metrics_provider->RegisterSource(
         metrics_file,
         metrics::FileMetricsProvider::SOURCE_HISTOGRAMS_ATOMIC_FILE,
         metrics::FileMetricsProvider::ASSOCIATE_PREVIOUS_RUN, metrics_name);
   } else {
     // When metrics reporting is not enabled, any existing file should be
     // deleted in order to preserve user privacy.
@@ skipping 34 matching lines @@
     // Register the Crashpad metrics files.
     // Register the data from the previous run if crashpad_handler didn't exit
     // cleanly.
     RegisterOrRemovePreviousRunMetricsFile(
         metrics_reporting_enabled, user_data_dir,
         kCrashpadHistogramAllocatorName, task_runner,
         file_metrics_provider.get());
     if (metrics_reporting_enabled) {
       base::FilePath active_path;
       base::GlobalHistogramAllocator::ConstructFilePaths(
-          user_data_dir, kCrashpadHistogramAllocatorName, nullptr,
-          &active_path);
+          user_data_dir, kCrashpadHistogramAllocatorName, nullptr, &active_path,
+          nullptr);
       // Register data that will be populated for the current run. "Active"
       // files need an empty "prefs_key" because they update the file itself.
       file_metrics_provider->RegisterSource(
           active_path,
           metrics::FileMetricsProvider::SOURCE_HISTOGRAMS_ACTIVE_FILE,
           metrics::FileMetricsProvider::ASSOCIATE_CURRENT_RUN,
           base::StringPiece());
     }
   }
 
@@ skipping 750 matching lines @@
     ukm_service_->Purge();
     ukm_service_->ResetClientId();
   }
   // Signal service manager to enable/disable UKM based on new state.
   UpdateRunningServices();
 }
 
 bool ChromeMetricsServiceClient::IsHistorySyncEnabledOnAllProfiles() {
   return SyncDisableObserver::IsHistorySyncEnabledOnAllProfiles();
 }