Stop setting use_qualified_include to true now that that is the default.

extensions/BUILD.gn

Index: extensions/BUILD.gn
diff --git a/extensions/BUILD.gn b/extensions/BUILD.gn
index e05952b2edb80268db4738560fc1021c075f54c3..db02ee847adffeee2b58774c72624c2f8d1a71b3 100644
--- a/extensions/BUILD.gn
+++ b/extensions/BUILD.gn
@@ -18,7 +18,6 @@ group("extensions_resources") {
 
 grit("extensions_resources_grd") {
   source = "extensions_resources.grd"
-  use_qualified_include = true
   outputs = [
     "grit/extensions_resources.h",
     "extensions_resources.pak",
@@ -27,10 +26,6 @@ grit("extensions_resources_grd") {
 
 grit("extensions_browser_resources") {
   source = "browser/resources/extensions_browser_resources.grd"
-
-  # TODO(thakis): Enable, https://crbug.com/401588
-  #use_qualified_include = true
-
   outputs = [
     "grit/extensions_browser_resources.h",
     "grit/extensions_browser_resources_map.cc",
@@ -46,7 +41,6 @@ grit("extensions_browser_resources") {
 
 grit("extensions_renderer_resources") {
   source = "renderer/resources/extensions_renderer_resources.grd"
-  use_qualified_include = true
   outputs = [
     "grit/extensions_renderer_resources.h",
     "extensions_renderer_resources.pak",