Remove some global defines and build flags.

tools/grit/grit_rule.gni

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Instantiate grit. This will produce a script target to run grit, and a
 # static library that compiles the .cc files.
 #
 # Parameters
 #
 #   source (required)
@@ skipping 168 matching lines @@
   ]
 }
 
 if (use_ozone) {
   grit_defines += [
     "-D",
     "use_ozone",
   ]
 }
 
-if (enable_image_loader_extension) {
-  grit_defines += [
-    "-D",
-    "image_loader_extension",
-  ]
-}
-
 if (is_android) {
   grit_defines += [
     "-E",
     "ANDROID_JAVA_TAGGED_ONLY=true",
   ]
 }
 
 if (is_mac || is_ios) {
   grit_defines += [
     "-D",
@@ skipping 315 matching lines @@
     if (defined(invoker.configs)) {
       configs += invoker.configs
     }
 
     if (defined(invoker.visibility)) {
       visibility = invoker.visibility
     }
     output_name = grit_output_name
   }
 }