Add incremental_apk_by_default GN arg.

chrome/test/android/chrome_public_test_support/BUILD.gn

 # Copyright 2015 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/rules.gni")
 
 android_apk("chrome_public_test_support_apk") {
+  # Used as an additional_apk in test scripts.
+  never_incremental = true
   deps = [
     "//chrome/test/android/cast_emulator:cast_emulator",
   ]
 
   apk_name = "ChromePublicTestSupport"
   android_manifest = "AndroidManifest.xml"
 }