Add updater state for Mac.

components/update_client/BUILD.gn

Index: components/update_client/BUILD.gn
diff --git a/components/update_client/BUILD.gn b/components/update_client/BUILD.gn
index b6061163062afc8da2c857b491363239d1c144a2..0a66f436023eb841fd3bbe97e776cd593e5d58fd 100644
--- a/components/update_client/BUILD.gn
+++ b/components/update_client/BUILD.gn
@@ -47,6 +47,7 @@ static_library("update_client") {
     "update_response.h",
     "updater_state.cc",
     "updater_state.h",
+    "updater_state_mac.mm",
     "updater_state_win.cc",
     "url_fetcher_downloader.cc",
     "url_fetcher_downloader.h",
@@ -68,6 +69,10 @@ static_library("update_client") {
     "//third_party/zlib:zip",
     "//url",
   ]
+  libs = []
+  if (is_mac) {
+    libs += [ "OpenDirectory.framework" ]
+  }
 }
 
 static_library("test_support") {