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

base/BUILD.gn

Index: base/BUILD.gn
diff --git a/base/BUILD.gn b/base/BUILD.gn
index f764c0aa1157b405548d94dc31ab2d2be9be4b02..8cc2bcfa97f565b961a3d85db3386315550f8676 100644
--- a/base/BUILD.gn
+++ b/base/BUILD.gn
@@ -600,13 +600,6 @@ component("base") {
     "power_monitor/power_monitor.h",
     "power_monitor/power_monitor_device_source.cc",
     "power_monitor/power_monitor_device_source.h",
-    "power_monitor/power_monitor_device_source_android.cc",
-    "power_monitor/power_monitor_device_source_android.h",
-    "power_monitor/power_monitor_device_source_chromeos.cc",
-    "power_monitor/power_monitor_device_source_ios.mm",
-    "power_monitor/power_monitor_device_source_mac.mm",
-    "power_monitor/power_monitor_device_source_posix.cc",
-    "power_monitor/power_monitor_device_source_win.cc",
     "power_monitor/power_monitor_source.cc",
     "power_monitor/power_monitor_source.h",
     "power_monitor/power_observer.h",
@@ -1076,10 +1069,7 @@ component("base") {
 
   # Android.
   if (is_android) {
-    sources -= [
-      "debug/stack_trace_posix.cc",
-      "power_monitor/power_monitor_device_source_posix.cc",
-    ]
+    sources -= [ "debug/stack_trace_posix.cc" ]
 
     # Android uses some Linux sources, put those back.
     set_sources_assignment_filter([])
@@ -1087,6 +1077,8 @@ component("base") {
       "debug/proc_maps_linux.cc",
       "files/file_path_watcher_linux.cc",
       "posix/unix_domain_socket_linux.cc",
+      "power_monitor/power_monitor_device_source_android.cc",
+      "power_monitor/power_monitor_device_source_android.h",
       "process/internal_linux.cc",
       "process/memory_linux.cc",
       "process/process_handle_linux.cc",
@@ -1109,7 +1101,7 @@ component("base") {
 
   # Chromeos.
   if (is_chromeos) {
-    sources -= [ "power_monitor/power_monitor_device_source_posix.cc" ]
+    sources += [ "power_monitor/power_monitor_device_source_chromeos.cc" ]
   }
 
   # NaCl.
@@ -1202,6 +1194,7 @@ component("base") {
   # Windows.
   if (is_win) {
     sources += [
+      "power_monitor/power_monitor_device_source_win.cc",
       "profiler/win32_stack_frame_unwinder.cc",
       "profiler/win32_stack_frame_unwinder.h",
     ]
@@ -1310,6 +1303,8 @@ component("base") {
 
   # Desktop Mac.
   if (is_mac) {
+    sources += [ "power_monitor/power_monitor_device_source_mac.mm" ]
+
     libs = [
       "ApplicationServices.framework",
       "AppKit.framework",
@@ -1443,6 +1438,7 @@ component("base") {
       "memory/shared_memory_posix.cc",
       "message_loop/message_pump_mac.h",
       "message_loop/message_pump_mac.mm",
+      "power_monitor/power_monitor_device_source_ios.mm",
       "process/memory_stubs.cc",
       "strings/sys_string_conversions_mac.mm",
       "threading/platform_thread_mac.mm",
@@ -1452,6 +1448,10 @@ component("base") {
     set_sources_assignment_filter(sources_assignment_filter)
   }
 
+  if (is_posix && !is_mac && !is_ios && !is_android && !is_chromeos) {
+    sources += [ "power_monitor/power_monitor_device_source_posix.cc" ]
+  }
+
   if (!use_glib) {
     sources -= [
       "message_loop/message_pump_glib.cc",