Do not register synthetic field trial before initializing TaskScheduler.

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 872 matching lines @@
       command_line->HasSwitch(switches::kTraceUploadURL)) {
     tracing::SetupNavigationTracing();
   }
 
   // Initialize FieldTrialSynchronizer system. This is a singleton and is used
   // for posting tasks via base::Bind. Its deleted when it goes out of scope.
   // Even though base::Bind does AddRef and Release, the object will not be
   // deleted after the Task is executed.
   field_trial_synchronizer_ = new FieldTrialSynchronizer();
 
-  // Register a synthetic field trial for the sampling profiler configuration
-  // that was already chosen.
-  std::string trial_name, group_name;
-  if (sampling_profiler_config_.GetSyntheticFieldTrial(&trial_name,
-                                                       &group_name)) {
-    ChromeMetricsServiceAccessor::RegisterSyntheticFieldTrial(trial_name,
-                                                              group_name);
-  }
-
 #if defined(OS_WIN) || defined(OS_MACOSX) || \
     (defined(OS_LINUX) && !defined(OS_CHROMEOS))
   metrics::DesktopSessionDurationTracker::Initialize();
 #endif
 
 #if defined(OS_WIN)
   // Cleanup the PreRead field trial registry key.
   // TODO(fdoray): Remove this when M56 hits stable.
   const base::string16 pre_read_field_trial_registry_path =

[robliao, 2016/09/30 18:10:56]

This is intended to be in this CL or a different CL?

[fdoray, 2016/09/30 19:06:40]

I did not change this block of code in this CL. I just moved the code related to
sampling profiler.

[robliao, 2016/09/30 19:08:10]

My mistake. I looked at the wrong diff mode!

       BrowserDistribution::GetDistribution()->GetRegistryPath() +
       L"\\PreReadFieldTrial";
   base::win::RegKey(HKEY_CURRENT_USER,
                     pre_read_field_trial_registry_path.c_str(), KEY_SET_VALUE)
       .DeleteKey(L"");
 #endif  // defined(OS_WIN)
 }
 
 void ChromeBrowserMainParts::SetupMetrics() {
   TRACE_EVENT0("startup", "ChromeBrowserMainParts::SetupMetrics");
@@ skipping 19 matching lines @@
       break;
   }
 }
 
 void ChromeBrowserMainParts::StartMetricsRecording() {
   TRACE_EVENT0("startup", "ChromeBrowserMainParts::StartMetricsRecording");
 
   g_browser_process->metrics_service()->CheckForClonedInstall(
       BrowserThread::GetTaskRunnerForThread(BrowserThread::FILE));
 
+  // Register a synthetic field trial for the sampling profiler configuration
+  // that was already chosen.
+  std::string trial_name, group_name;
+  if (sampling_profiler_config_.GetSyntheticFieldTrial(&trial_name,
+                                                       &group_name)) {
+    ChromeMetricsServiceAccessor::RegisterSyntheticFieldTrial(trial_name,
+                                                              group_name);
+  }
+
   g_browser_process->GetMetricsServicesManager()->UpdateUploadPermissions(true);
 }
 
 void ChromeBrowserMainParts::RecordBrowserStartupTime() {
   // Don't record any metrics if UI was displayed before this point e.g.
   // warning dialogs.
   if (startup_metric_utils::WasNonBrowserUIDisplayed())
     return;
 
   bool is_first_run = false;
@@ skipping 1263 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);
 }