Move the thread hop for UMA user actions from content:: to base::.

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 <set>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/at_exit.h"
 #include "base/base_switches.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/crash_logging.h"
 #include "base/debug/debugger.h"
 #include "base/feature_list.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
+#include "base/metrics/user_metrics.h"
 #include "base/path_service.h"
 #include "base/profiler/scoped_profile.h"
 #include "base/profiler/scoped_tracker.h"
 #include "base/run_loop.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_piece.h"
 #include "base/strings/string_split.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/sys_info.h"
@@ skipping 624 matching lines @@
   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).
 
+  base::SetRecordActionTaskRunner(
+      BrowserThread::GetMessageLoopProxyForThread(BrowserThread::UI));

[piman, 2016/04/18 21:13:08]

Should this be done in content/ ? There are tests (e.g. layout tests) and other
embedders that don't use chrome/

[beaudoin, 2016/04/19 16:57:27]

asvitkine@ for opinions.

My opinion is that other embedders and/or tests are likely to need a different
task runner and should set it up. I've done it in user_action_tester.cc using a
custom SimpleTaskRunner.

[Alexei Svitkine (slow), 2016/04/19 17:56:41]

Yeah, since this only affects cases where AddActionCallback() has been used to
set a callback, I don't think it's needed in content - since that is not
currently done in content. At least with this CL.

I guess if we do want to start using this from content in a future CL, then it
can be done at that point.

+
   // Initialize FieldTrialList to support FieldTrials that use one-time
   // randomization.
   metrics::MetricsService* metrics = browser_process_->metrics_service();
   // TODO(asvitkine): Turn into a DCHECK after http://crbug.com/359406 is fixed.
   CHECK(!field_trial_list_);
   // TODO(asvitkine): Remove this after http://crbug.com/359406 is fixed.
   base::FieldTrialList::EnableGlobalStateChecks();
   field_trial_list_.reset(
       new base::FieldTrialList(metrics->CreateEntropyProvider().release()));
 
@@ skipping 1269 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);
 }