Revert of Move prefix_set and parts of s_b_util into a new component safe_browsing_db.

components/safe_browsing_db.gypi

-# 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.
-
-{
-  'targets': [
-    {
-      # GN version: //components/safe_browsing_db
-      'target_name': 'safe_browsing_db',
-      'type': 'static_library',
-      'dependencies': [
-        '../base/base.gyp:base',
-        '../crypto/crypto.gyp:crypto',
-      ],
-      'sources': [
-        # Note: sources list duplicated in GN build.
-        'safe_browsing_db/prefix_set.h',
-        'safe_browsing_db/prefix_set.cc',
-        'safe_browsing_db/safe_browsing_db_util.h',
-        'safe_browsing_db/safe_browsing_db_util.cc',
-      ],
-      'include_dirs': [
-        '..',
-      ],
-    },
-  ],
-}