Fix ios_chrome_unittests to crash on DCHECK failure.

ios/chrome/browser/metrics/first_user_action_recorder.cc

 // Copyright 2013 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/metrics/first_user_action_recorder.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/string_util.h"
@@ skipping 73 matching lines @@
 }  // namespace
 
 FirstUserActionRecorder::FirstUserActionRecorder(
     base::TimeDelta background_duration)
     : device_family_(IsIPadIdiom() ? TABLET : HANDSET),
       recorded_action_(false),
       action_pending_(false),
       background_duration_(background_duration),
       action_callback_(base::Bind(&FirstUserActionRecorder::OnUserAction,
                                   base::Unretained(this))) {
-  base::SetRecordActionTaskRunner(
-      web::WebThread::GetTaskRunnerForThread(web::WebThread::UI));
   base::AddActionCallback(action_callback_);
 }
 
 FirstUserActionRecorder::~FirstUserActionRecorder() {
   base::RemoveActionCallback(action_callback_);
 }
 
 void FirstUserActionRecorder::Expire() {
   std::string log_message = "Recording 'Expiration' for first user action type";
   RecordAction(EXPIRATION, log_message);
@@ skipping 91 matching lines @@
 
 bool FirstUserActionRecorder::ArrayContainsString(const char* to_search[],
                                                   const size_t to_search_size,
                                                   const char* to_find) {
   for (size_t i = 0; i < to_search_size; ++i) {
     if (strcmp(to_find, to_search[i]) == 0)
       return true;
   }
   return false;
 }