Remove som GYP annotations, remove unused manifest.

testing/android/driver/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/rules.gni")
 
-# GYP: //testing/android/on_device_instrumentation.gyp:driver_apk
 android_apk("driver_apk") {
   android_manifest = "java/AndroidManifest.xml"
   apk_name = "OnDeviceInstrumentationDriver"
   testonly = true
 
   deps = [
     "//base:base_java",
     "//base:base_java_test_support",
     "//testing/android/appurify_support:appurify_support_java",
     "//testing/android/broker:broker_java",
     "//testing/android/reporter:reporter_java",
   ]
 
   java_files =
       [ "java/src/org/chromium/test/driver/OnDeviceInstrumentationDriver.java" ]
 }