Revert of delete the levelDB storage implementation.

components/offline_pages.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: //components/offline_pages:offline_pages
       'target_name': 'offline_pages',
       'type': 'static_library',
       'include_dirs': [
         '..',
       ],
       'dependencies': [
         '../base/base.gyp:base',
         '../net/net.gyp:net',
         '../url/url.gyp:url_lib',
         '../sql/sql.gyp:sql',
+        '../third_party/leveldatabase/leveldatabase.gyp:leveldatabase',
+        'components.gyp:leveldb_proto',
         'keyed_service_core',
+        'offline_pages_proto',
       ],
       'sources': [
         'offline_pages/archive_manager.cc',
         'offline_pages/archive_manager.h',
         'offline_pages/client_policy_controller.cc',
         'offline_pages/client_policy_controller.h',
         'offline_pages/offline_page_archiver.h',
         'offline_pages/offline_page_client_policy.h',
         'offline_pages/offline_page_feature.cc',
         'offline_pages/offline_page_feature.h',
         'offline_pages/offline_page_item.cc',
         'offline_pages/offline_page_item.h',
         'offline_pages/offline_page_metadata_store.cc',
         'offline_pages/offline_page_metadata_store.h',
+        'offline_pages/offline_page_metadata_store_impl.cc',
+        'offline_pages/offline_page_metadata_store_impl.h',
         'offline_pages/offline_page_model.cc',
         'offline_pages/offline_page_model.h',
         'offline_pages/offline_page_storage_manager.cc',
         'offline_pages/offline_page_storage_manager.h',
         'offline_pages/offline_page_types.h',
         'offline_pages/snapshot_controller.cc',
         'offline_pages/snapshot_controller.h',
         'offline_pages/offline_page_metadata_store_sql.cc',
         'offline_pages/offline_page_metadata_store_sql.h',
       ],
@@ skipping 38 matching lines @@
         '../url/url.gyp:url_lib',
         'offline_pages',
       ],
       'sources': [
         'offline_pages/offline_page_test_archiver.h',
         'offline_pages/offline_page_test_archiver.cc',
         'offline_pages/offline_page_test_store.h',
         'offline_pages/offline_page_test_store.cc',
       ],
     },
+    {
+      # Protobuf compiler / generator for the offline page item protocol buffer.
+      # GN version: //components/offline_pages/proto
+      'target_name': 'offline_pages_proto',
+      'type': 'static_library',
+      'sources': [ 'offline_pages/proto/offline_pages.proto', ],
+      'variables': {
+        'proto_in_dir': 'offline_pages/proto',
+        'proto_out_dir': 'components/offline_pages/proto',
+      },
+      'includes': [ '../build/protoc.gypi', ],
+    },
   ],
   'conditions': [
     ['OS == "android"', {
       'targets': [
         {
           # GN: //components/offline_pages:offline_page_model_enums_java
           'target_name': 'offline_page_model_enums_java',
           'type': 'none',
           'variables': {
             'source_file': 'offline_pages/offline_page_types.h',
           },
           'includes': [ '../build/android/java_cpp_enum.gypi' ],
         },
       ],
     }],
   ],
 }