Add use_rtti flag to control Run-Time Type Identification

build/config/BUILDCONFIG.gn

Index: build/config/BUILDCONFIG.gn
diff --git a/build/config/BUILDCONFIG.gn b/build/config/BUILDCONFIG.gn
index c8b19d770c53cdee412b2554df689d558d161f3c..8ea9cd51a460b2e996b682b5897df41022fecccb 100644
--- a/build/config/BUILDCONFIG.gn
+++ b/build/config/BUILDCONFIG.gn
@@ -162,6 +162,9 @@ declare_args() {
   # For more information see
   # https://chromium.googlesource.com/chromium/src/+/master/docs/component_build.md
   is_component_build = is_debug && current_os != "ios"
+
+  # Run-Time Type Identification.
+  use_rtti = false

[kjellander_chromium, 2017/01/02 07:47:14]

Let me know if there's a better place to put this.

 }
 
 assert(!(is_debug && is_official_build), "Can't do official debug builds")
@@ -480,10 +483,14 @@ default_compiler_configs = [
   "//build/config/compiler:default_optimization",
   "//build/config/compiler:default_stack_frames",
   "//build/config/compiler:default_symbols",
-  "//build/config/compiler:no_rtti",
   "//build/config/compiler:runtime_library",
   "//build/config/sanitizers:default_sanitizer_flags",
 ]
+if (use_rtti) {
+  default_compiler_configs += [ "//build/config/compiler:rtti" ]
+} else {
+  default_compiler_configs += [ "//build/config/compiler:no_rtti" ]
+}
 if (is_win) {
   default_compiler_configs += [
     "//build/config/win:default_crt",