Add incremental_apk_by_default GN arg.

chrome/android/webapk/shell_apk/javatests/dex_optimizer/BUILD.gn

 # Copyright 2016 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/rules.gni")
 
 android_aidl("dex_optimizer_service_aidl") {
   interface_file =
       "src/org/chromium/webapk/shell_apk/test/dex_optimizer/common.aidl"
   sources = [
     "src/org/chromium/webapk/shell_apk/test/dex_optimizer/IDexOptimizerService.aidl",
   ]
 }
 
 android_apk("dex_optimizer_apk") {
+  # Used as an additional_apk in test scripts.
+  never_incremental = true
   android_manifest = "AndroidManifest.xml"
   apk_name = "DexOptimizer"
   chromium_code = false
   java_files = [ "src/org/chromium/webapk/shell_apk/test/dex_optimizer/DexOptimizerServiceImpl.java" ]
   deps = [
     "//base:base_java",
     "//chrome/android/webapk/libs/client:client_java",
     "//chrome/android/webapk/shell_apk/javatests/canary_lib:canary_dex2_assets",
     "//chrome/android/webapk/shell_apk/javatests/canary_lib:canary_dex_assets",
   ]
   srcjar_deps = [ ":dex_optimizer_service_aidl" ]
 }