Move EntropyProvider Source From MetricsService to MetricsServicesManager

chrome/browser/chrome_browser_main.cc

 // Copyright (c) 2012 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/chrome_browser_main.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 776 matching lines @@
 
 ChromeBrowserMainParts::~ChromeBrowserMainParts() {
   for (int i = static_cast<int>(chrome_extra_parts_.size())-1; i >= 0; --i)
     delete chrome_extra_parts_[i];
   chrome_extra_parts_.clear();
 }
 
 // This will be called after the command-line has been mutated by about:flags
 void ChromeBrowserMainParts::SetupMetricsAndFieldTrials() {
   TRACE_EVENT0("startup", "ChromeBrowserMainParts::SetupMetricsAndFieldTrials");
-  // Must initialize metrics after labs have been converted into switches,
-  // but before field trials are set up (so that client ID is available for
-  // one-time randomized field trials).
 
   // Initialize FieldTrialList to support FieldTrials that use one-time
   // randomization.
-  metrics::MetricsService* metrics = browser_process_->metrics_service();
-
   DCHECK(!field_trial_list_);
   field_trial_list_.reset(
-      new base::FieldTrialList(metrics->CreateEntropyProvider().release()));
+      new base::FieldTrialList(browser_process_->GetMetricsServicesManager()
+                                   ->CreateEntropyProvider()

[brettw, 2016/09/14 22:22:03]

A nice and easy follow-up to this patch would be to fix FieldTrialList to take a
unique_ptr which would improve this code.

[robliao, 2016/09/15 14:31:18]

Agreed to that.

+                                   .release()));
 
   const base::CommandLine* command_line =
       base::CommandLine::ForCurrentProcess();
   if (command_line->HasSwitch(switches::kEnableBenchmarking) ||
       command_line->HasSwitch(cc::switches::kEnableGpuBenchmarking)) {
     base::FieldTrial::EnableBenchmarking();
   }
 
   if (command_line->HasSwitch(switches::kForceFieldTrialParams)) {
     bool result = chrome_variations::AssociateParamsFromString(
@@ skipping 20 matching lines @@
 
   std::unique_ptr<base::FeatureList> feature_list(new base::FeatureList);
 
   // Associate parameters chosen in about:flags and create trial/group for them.
   flags_ui::PrefServiceFlagsStorage flags_storage(
       g_browser_process->local_state());
   std::vector<std::string> variation_ids =
       about_flags::RegisterAllFeatureVariationParameters(
           &flags_storage, feature_list.get());
 
+  // Must initialize metrics after about:flags have been converted into
+  // switches, but before field trials are set up (so that client ID is
+  // available for one-time randomized field trials).
+  metrics::MetricsService* metrics = browser_process_->metrics_service();
+
   variations::VariationsHttpHeaderProvider* http_header_provider =
       variations::VariationsHttpHeaderProvider::GetInstance();
   // Force the variation ids selected in chrome://flags and/or specified using
   // the command-line flag.
   bool result = http_header_provider->ForceVariationIds(
       command_line->GetSwitchValueASCII(switches::kForceVariationIds),
       &variation_ids);
   CHECK(result) << "Invalid list of variation ids specified (either in --"
                 << switches::kForceVariationIds << " or in chrome://flags)";
   metrics->AddSyntheticTrialObserver(http_header_provider);
@@ skipping 1349 matching lines @@
   chromeos::CrosSettings::Shutdown();
 #endif  // defined(OS_CHROMEOS)
 #endif  // defined(OS_ANDROID)
 }
 
 // Public members:
 
 void ChromeBrowserMainParts::AddParts(ChromeBrowserMainExtraParts* parts) {
   chrome_extra_parts_.push_back(parts);
 }