GN: Move configs for single-use Linux packages close to usage

chrome/browser/ui/libgtk2ui/BUILD.gn

Index: chrome/browser/ui/libgtk2ui/BUILD.gn
diff --git a/chrome/browser/ui/libgtk2ui/BUILD.gn b/chrome/browser/ui/libgtk2ui/BUILD.gn
index 6fc67c12c6b5127ed38dc667cb6ce6b5ca81e521..0d34b7a1a5be1baddb5d94857396fbccb6eb1b10 100644
--- a/chrome/browser/ui/libgtk2ui/BUILD.gn
+++ b/chrome/browser/ui/libgtk2ui/BUILD.gn
@@ -5,6 +5,17 @@
 assert(is_linux, "This file should only be referenced on Linux")
 
 import("//build/config/features.gni")
+import("//build/config/linux/pkg_config.gni")
+
+pkg_config("gtk") {
+  # Gtk requires gmodule, but it does not list it as a dependency in some
+  # misconfigured systems.
+  packages = [ "gmodule-2.0", "gtk+-2.0", "gthread-2.0" ]
+}
+
+pkg_config("gtkprint") {
+  packages = [ "gtk+-unix-print-2.0" ]
+}
 
 component("libgtk2ui") {
   sources = [
@@ -70,9 +81,9 @@ component("libgtk2ui") {
   defines = [ "LIBGTK2UI_IMPLEMENTATION" ]
 
   configs += [
+    ":gtk",
+    ":gtkprint",
     "//build/config/linux:gconf",
-    "//build/config/linux:gtk",
-    "//build/config/linux:gtkprint",
     "//printing:cups",
   ]