Remove non-monotonic clock support

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")
@@ skipping 82 matching lines @@
   deps = [
     "..:webrtc_common",
   ]
 
   if (is_android) {
     sources += [
       "include/logcat_trace_context.h",
       "source/logcat_trace_context.cc",
     ]
 
-    defines += [
-      "WEBRTC_THREAD_RR",
-
-      # TODO(leozwang): Investigate CLOCK_REALTIME and CLOCK_MONOTONIC
-      # support on Android. Keep WEBRTC_CLOCK_TYPE_REALTIME for now,
-      # remove it after I verify that CLOCK_MONOTONIC is fully functional
-      # with condition and event functions in system_wrappers.
-      "WEBRTC_CLOCK_TYPE_REALTIME",
-    ]
+    defines += [ "WEBRTC_THREAD_RR" ]
 
     deps += [ ":cpu_features_android" ]
 
     libs += [ "log" ]
   }
 
   if (is_linux) {
-    defines += [
-      "WEBRTC_THREAD_RR",
-      # TODO(andrew): can we select this automatically?
-      # Define this if the Linux system does not support CLOCK_MONOTONIC.
-      #"WEBRTC_CLOCK_TYPE_REALTIME",
-    ]
+    defines += [ "WEBRTC_THREAD_RR" ]
 
     libs += [ "rt" ]
   }
 
   if (!is_mac && !is_ios) {
     sources += [ "source/atomic32_posix.cc" ]
   }
 
   if (is_ios || is_mac) {
-    defines += [
-      "WEBRTC_THREAD_RR",
-      "WEBRTC_CLOCK_TYPE_REALTIME",
-    ]
+    defines += [ "WEBRTC_THREAD_RR" ]
   }
 
   if (is_ios) {
     sources += [ "source/atomic32_mac.cc" ]
   }
 
   if (is_win) {
     libs += [ "winmm.lib" ]
 
     cflags = [
@@ skipping 41 matching lines @@
       "source/cpu_features_android.c",
     ]
 
     configs += [ "..:common_config" ]
     public_configs = [ "..:common_inherited_config" ]
     deps = [
       "//third_party/android_tools:cpu_features",
     ]
   }
 }