Fix iOS GN build and cleanup system_wrappers

webrtc/system_wrappers/BUILD.gn

 # Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 import("//build/config/android/config.gni")
 import("../build/webrtc.gni")
 
 static_library("system_wrappers") {
   sources = [
     "include/aligned_array.h",
     "include/aligned_malloc.h",
     "include/atomic32.h",
     "include/clock.h",
     "include/cpu_features_wrapper.h",
     "include/cpu_info.h",
     "include/critical_section_wrapper.h",
     "include/data_log.h",
     "include/data_log_c.h",
     "include/data_log_impl.h",
     "include/event_wrapper.h",
     "include/field_trial.h",
     "include/file_wrapper.h",
     "include/fix_interlocked_exchange_pointer_win.h",
     "include/logging.h",
     "include/metrics.h",
+    "include/ntp_time.h",
     "include/rtp_to_ntp.h",
     "include/rw_lock_wrapper.h",
     "include/sleep.h",
     "include/sort.h",
     "include/static_instance.h",
     "include/stl_util.h",
     "include/stringize_macros.h",
     "include/timestamp_extrapolator.h",
     "include/trace.h",
     "include/utf_util_win.h",
     "source/aligned_malloc.cc",
-    "source/atomic32_mac.cc",
     "source/atomic32_win.cc",
     "source/clock.cc",
     "source/condition_variable_event_win.cc",
     "source/condition_variable_event_win.h",
     "source/cpu_features.cc",
     "source/cpu_info.cc",
     "source/data_log_c.cc",
     "source/event.cc",
     "source/event_timer_posix.cc",
     "source/event_timer_posix.h",
@@ skipping 53 matching lines @@
   if (is_linux) {
     defines += [ "WEBRTC_THREAD_RR" ]
 
     if (!build_with_chromium) {
       deps += [ ":cpu_features_linux" ]
     }
 
     libs += [ "rt" ]
   }
 
-  if (!is_mac && !is_ios) {
-    sources += [ "source/atomic32_posix.cc" ]
+  if (is_linux || is_android) {
+    sources += [ "source/atomic32_non_darwin_unix.cc" ]
   }
 
   if (is_ios || is_mac) {
     defines += [ "WEBRTC_THREAD_RR" ]
-  }
-
-  if (is_ios) {
-    sources += [ "source/atomic32_mac.cc" ]
+    sources += [ "source/atomic32_darwin.cc" ]
   }
 
   if (is_win) {
     libs += [ "winmm.lib" ]
 
     cflags = [
       "/wd4267",  # size_t to int truncation.
       "/wd4334",  # Ignore warning on shift operator promotion.
     ]
   }
@@ skipping 49 matching lines @@
 if (is_linux) {
   source_set("cpu_features_linux") {
     sources = [
       "source/cpu_features_linux.c",
     ]
 
     configs += [ "..:common_config" ]
     public_configs = [ "..:common_inherited_config" ]
   }
 }