Remove proguard specific override block

build/config/android/rules.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.
 
 import("//build/config/android/config.gni")
 import("//build/config/android/internal_rules.gni")
 import("//build/toolchain/toolchain.gni")
 
 assert(is_android)
 
@@ skipping 2309 matching lines @@
       }
     }
 
     android_apk(target_name) {
       set_sources_assignment_filter([])
       data_deps = []
       deps = []
       forward_variables_from(invoker, "*")
       testonly = true
 
-      if (defined(invoker.proguard_enabled) && invoker.proguard_enabled) {
-        assert(invoker.proguard_configs != [])
-        proguard_enabled = true
-        proguard_configs = invoker.proguard_configs
-      }
+      assert(!defined(invoker.proguard_enabled) || !invoker.proguard_enabled
+             || invoker.proguard_configs != [])
 
       if (!defined(apk_name)) {
         apk_name = get_label_info(invoker.shared_library, "name")
       }
 
       if (!defined(android_manifest)) {
         android_manifest_dep = ":${target_name}_manifest"
         android_manifest = _android_manifest
       }
 
@@ skipping 148 matching lines @@
     android_library(target_name) {
       chromium_code = false
       java_files = []
       srcjar_deps = [ ":${_template_name}__protoc_java" ]
       deps = [
         "//third_party/android_protobuf:protobuf_nano_javalib",
       ]
     }
   }
 }