Remove the code added to make extensions compile on Aura Android.

extensions/common/api/printer_provider/usb_printer_manifest_handler_android.cc

-// 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.
-
-#include "extensions/common/api/printer_provider/usb_printer_manifest_handler.h"
-
-#include "extensions/common/extension.h"
-
-namespace extensions {
-
-UsbPrinterManifestHandler::UsbPrinterManifestHandler() {
-}
-
-UsbPrinterManifestHandler::~UsbPrinterManifestHandler() {
-}
-
-bool UsbPrinterManifestHandler::Parse(Extension* extension,
-                                      base::string16* error) {
-  return false;
-}
-
-const std::vector<std::string> UsbPrinterManifestHandler::Keys() const {
-  return std::vector<std::string>();
-}
-
-}  // namespace extensions