Add components/keyed_service to GN build.

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index e3feaf393b9572e110a5461b7ccb4eb3607b0839..248136f280c6c550ed123714fc7f4cf3e28bc9d4 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -110,6 +110,10 @@ group("root") {
     #deps += [ "//breakpad:symupload" ]
   }
 
+  if (!is_ios) {
+    deps += [ "//components/keyed_service/content" ]
+  }
+
   if (is_linux) {
     deps += [
       "//dbus",
@@ -140,6 +144,7 @@ group("root") {
     deps -= [
       "//cc",
       "//content",
+      "//components/keyed_service/content",  # Blocked on content.
       "//components/user_prefs",  # Blocked on content.
       "//components/visitedlink/browser",  # Blocked on content.
       "//components/visitedlink/common",  # Blocked on content.