Add GN build for some chrome common, chrome net, and resources targets.

Slight enhancements to the grit template.

R=thestig@chromium.org

Review URL: https://codereview.chromium.org/335053002

git-svn-id: http://src.chromium.org/svn/trunk/src/build@277517 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

config/features.gni

@@ -70,3 +70,5 @@ disable_ftp_support = is_ios
 enable_speech_input = true
 
 use_dbus = is_linux
+
+enable_extensions = (!is_android && !is_ios)