Use sysroot for chromeos builds

components/timers/alarm_timer_chromeos.cc

 // Copyright 2014 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 "components/timers/alarm_timer_chromeos.h"
 
 #include <stdint.h>
 #include <sys/timerfd.h>
 #include <utility>
 
@@ skipping 142 matching lines @@
   // OnTimerFired() runs |on_timer_fired_callback_| only if the sequence number
   // it receives from the MessageLoopForIO matches
   // |origin_reset_sequence_number_|.
   int origin_reset_sequence_number_;
   int io_reset_sequence_number_;
 
   DISALLOW_COPY_AND_ASSIGN(Delegate);
 };
 
 AlarmTimer::Delegate::Delegate(base::Closure on_timer_fired_callback)
+#ifdef CLOCK_REALTIME_ALARM
     : alarm_fd_(timerfd_create(CLOCK_REALTIME_ALARM, 0)),
+#else
+    : alarm_fd_(-1),
+#endif
       on_timer_fired_callback_(on_timer_fired_callback),
       origin_reset_sequence_number_(0),
       io_reset_sequence_number_(0) {
   // The call to timerfd_create above may fail.  This is the only indication
   // that CLOCK_REALTIME_ALARM is not supported on this system.
   DPLOG_IF(INFO, (alarm_fd_ == -1))
       << "CLOCK_REALTIME_ALARM not supported on this system";
 }
 
 AlarmTimer::Delegate::~Delegate() {
@@ skipping 292 matching lines @@
 SimpleAlarmTimer::SimpleAlarmTimer(const tracked_objects::Location& posted_from,
                                    base::TimeDelta delay,
                                    const base::Closure& user_task)
     : AlarmTimer(posted_from, delay, user_task, false) {
 }
 
 SimpleAlarmTimer::~SimpleAlarmTimer() {
 }
 
 }  // namespace timers