Implement base::PowerMonitor::IsOnBatteryPower() for OSX.

base/BUILD.gn

Index: base/BUILD.gn
diff --git a/base/BUILD.gn b/base/BUILD.gn
index a26be55dd92487a88efd937f6e8ab16c6e8ebbc8..17c9185c25657b38d96f34e3eca09e5677bd0aa8 100644
--- a/base/BUILD.gn
+++ b/base/BUILD.gn
@@ -1307,6 +1307,8 @@ component("base") {
 
   # Desktop Mac.
   if (is_mac) {
+    sources -= [ "power_monitor/power_monitor_device_source_posix.cc" ]

[Nico, 2016/09/20 00:04:13]

(fwiw, instead of "add all, then subtract", in gn we do "only add what we need
in the first place" -- so instead of removing it here, only add it if !is_mac
further up)

[DaleCurtis, 2016/09/21 22:49:39]

Done. Fixed all the existing cases.

+
     libs = [
       "ApplicationServices.framework",
       "AppKit.framework",