Enable -Wunused-local-typedef

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 0d34b7a1a5be1baddb5d94857396fbccb6eb1b10..c5e1668b56b3d8e544c37928d9f8657f89438087 100644
--- a/chrome/browser/ui/libgtk2ui/BUILD.gn
+++ b/chrome/browser/ui/libgtk2ui/BUILD.gn
@@ -72,12 +72,6 @@ component("libgtk2ui") {
       "gconf_listener.h",
     ]
   }
-  if (is_clang) {
-    # G_DEFINE_TYPE automatically generates a *get_instance_private inline
-    # function after glib 2.37. That's unused. Prevent to complain about it.
-    cflags = [ "-Wno-unused-function" ]
-  }
-
   defines = [ "LIBGTK2UI_IMPLEMENTATION" ]
 
   configs += [
@@ -87,6 +81,23 @@ component("libgtk2ui") {
     "//printing:cups",
   ]
 
+  # gn orders flags on a target before flags from configs. The default config
+  # adds -Wall, and these flags have to be after -Wall -- so they need to come
+  # from a config and can't be on the target directly.
+  config("libgtk2ui_warnings") {
+    if (is_clang) {
+      cflags = [
+        # G_DEFINE_TYPE automatically generates a *get_instance_private inline
+        # function after glib 2.37. That's unused. Prevent to complain about it.
+        "-Wno-unused-function",
+
+        # G_STATIC_ASSERT uses a typedef as a static_assert.
+        "-Wno-unused-local-typedef",
+      ]
+    }
+  }
+  configs += [ ":libgtk2ui_warnings", ]
+
   deps = [
     "//base",
     "//base:i18n",