Move EntropyProvider Source From MetricsService to MetricsServicesManager

ios/chrome/browser/ios_chrome_main_parts.mm

 // 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.
 
 #include "ios/chrome/browser/ios_chrome_main_parts.h"
 
 #include "base/base_switches.h"
 #include "base/feature_list.h"
 #include "base/files/file_path.h"
 #include "base/logging.h"
@@ skipping 175 matching lines @@
 
 void IOSChromeMainParts::PostDestroyThreads() {
   application_context_->PostDestroyThreads();
 }
 
 // This will be called after the command-line has been mutated by about:flags
 void IOSChromeMainParts::SetUpMetricsAndFieldTrials() {
   base::SetRecordActionTaskRunner(
       web::WebThread::GetTaskRunnerForThread(web::WebThread::UI));
 
-  // 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).
-  metrics::MetricsService* metrics = application_context_->GetMetricsService();
-
   // Initialize FieldTrialList to support FieldTrials that use one-time
   // randomization.

[Alexei Svitkine (slow), 2016/09/14 20:26:37]

Can you add the DCHECK() that's in the non-iOS code here too, for consistency?
Thanks!

[robliao, 2016/09/14 20:54:42]

Done.

   field_trial_list_.reset(
-      new base::FieldTrialList(metrics->CreateEntropyProvider().release()));
+      new base::FieldTrialList(application_context_->GetMetricsServicesManager()
+                                   ->CreateEntropyProvider()
+                                   .release()));
 
   const base::CommandLine* command_line =
       base::CommandLine::ForCurrentProcess();
   // Ensure any field trials specified on the command line are initialized.
   // Also stop the metrics service so that we don't pollute UMA.
   if (command_line->HasSwitch(switches::kForceFieldTrials)) {
     // Create field trials without activating them, so that this behaves in a
     // consistent manner with field trials created from the server.
     bool result = base::FieldTrialList::CreateTrialsFromString(
         command_line->GetSwitchValueASCII(switches::kForceFieldTrials),
         std::set<std::string>());
     CHECK(result) << "Invalid --" << switches::kForceFieldTrials
                   << " list specified.";
   }
 
   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(
       application_context_->GetLocalState());
   std::vector<std::string> variation_ids =
       RegisterAllFeatureVariationParameters(&flags_storage, feature_list.get());
 
+  // Must initialize metrics after labs have been converted into switches,

[Alexei Svitkine (slow), 2016/09/14 20:26:38]

Nit: "labs" terminology is pretty outdated. Given you're moving this, change
"labs" to "about:flags". Here and in the non-iOS one. In the non-iOS code move
the comment to the same place as here, please.

[robliao, 2016/09/14 20:54:42]

Done.

+  // but before field trials are set up (so that client ID is available for
+  // one-time randomized field trials).
+  metrics::MetricsService* metrics = application_context_->GetMetricsService();
+

[Alexei Svitkine (slow), 2016/09/14 20:26:38]

Nit: Make it consistent with the non-iOS code - either an empty line on both or
no empty line in both. (I don't have a preference either way).

[robliao, 2016/09/14 20:54:42]

This was lost in a file I forgot to save! It's there now.

   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::kIOSForceVariationIds),
       &variation_ids);
   CHECK(result) << "Invalid list of variation ids specified (either in --"
                 << switches::kIOSForceVariationIds << " or in chrome://flags)";
   metrics->AddSyntheticTrialObserver(http_header_provider);
@@ skipping 18 matching lines @@
 
 void IOSChromeMainParts::StartMetricsRecording() {
   bool wifiOnly = local_state_->GetBoolean(prefs::kMetricsReportingWifiOnly);
   bool isConnectionCellular = net::NetworkChangeNotifier::IsConnectionCellular(
       net::NetworkChangeNotifier::GetConnectionType());
   bool mayUpload = !wifiOnly || !isConnectionCellular;
 
   application_context_->GetMetricsServicesManager()->UpdateUploadPermissions(
       mayUpload);
 }