GN: Introduce templates.

webrtc/libjingle/xmllite/BUILD.gn

Index: webrtc/libjingle/xmllite/BUILD.gn
diff --git a/webrtc/libjingle/xmllite/BUILD.gn b/webrtc/libjingle/xmllite/BUILD.gn
index c35dde69e05eaf5e9773d4dcdf5fe4811361d1ee..936e2b9b9acda504766c240075f58c14c3c8f098 100644
--- a/webrtc/libjingle/xmllite/BUILD.gn
+++ b/webrtc/libjingle/xmllite/BUILD.gn
@@ -14,7 +14,7 @@ group("xmllite") {
   ]
 }
 
-source_set("rtc_xmllite") {
+rtc_source_set("rtc_xmllite") {
   sources = [
     "qname.cc",
     "qname.h",
@@ -49,6 +49,6 @@ source_set("rtc_xmllite") {
   if (!build_with_chromium && is_clang) {
     # Suppress warnings from Chrome's Clang plugins.
     # See http://code.google.com/p/webrtc/issues/detail?id=163 for details.
-    configs -= [ "//build/config/clang:find_bad_constructs" ]
+    suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
   }
 }