Enable building base.dll for the multi-dll build.

base/base.gypi

 # Copyright (c) 2011 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.
 
 {
   'target_defaults': {
     'variables': {
       'base_target': 0,
     },
     'target_conditions': [
@@ skipping 404 matching lines @@
               'base/files/file_path_watcher_stub.cc',
             ],
           }],
         ],
       }],
     ],
   },
   'targets': [
     {
       'target_name': 'base',
-      'type': '<(library)',
+      'type': '<(component)',
       'msvs_guid': '1832A374-8A74-4F9E-B536-69A699B3E165',
       'variables': {
         'base_target': 1,
       },
       'dependencies': [
         'base_static',
         '../third_party/modp_b64/modp_b64.gyp:modp_b64',
         'third_party/dynamic_annotations/dynamic_annotations.gyp:dynamic_annotations',
       ],
       'export_dependent_settings': [
@@ skipping 84 matching lines @@
               'third_party/purify/pure_api.c',
               'base_drag_source.cc',
               'base_drop_target.cc',
               'event_recorder.cc',
               'file_version_info.cc',
               'registry.cc',
               'resource_util.cc',
               'win_util.cc',
             ],
         },],
+        [ 'OS=="win" and component=="shared_library"', {
+          'defines': [
+            'BASE_DLL',
+            'BASE_IMPLEMENTATION=1',
+          ],
+          'msvs_disabled_warnings': [
+            4251,
+          ],
+          'sources!': [
+            'debug/debug_on_start_win.cc',
+          ],
+          'direct_dependent_settings': {
+            'defines': [
+              'BASE_DLL',
+            ],
+            'msvs_disabled_warnings': [
+              4251,
+            ],
+          },
+        }],
       ],
       'sources': [
         'third_party/nspr/prcpucfg.h',
         'third_party/nspr/prcpucfg_win.h',
         'third_party/nspr/prtypes.h',
         'third_party/purify/pure.h',
         'third_party/purify/pure_api.c',
         'third_party/xdg_user_dirs/xdg_user_dir_lookup.cc',
         'third_party/xdg_user_dirs/xdg_user_dir_lookup.h',
         'auto_reset.h',
@@ skipping 116 matching lines @@
             'third_party/xdg_mime/xdgmimemagic.c',
             'third_party/xdg_mime/xdgmimemagic.h',
             'third_party/xdg_mime/xdgmimeparent.c',
             'third_party/xdg_mime/xdgmimeparent.h',
           ],
         },
       ],
     }],
   ],
 }