Introduce ui.dll / libui.so for the component build.

build/common.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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 868 matching lines @@
             ],
             'msvs_disabled_warnings': [4800],
             'msvs_settings': {
               'VCCLCompilerTool': {
                 'WarningLevel': '3',
                 'WarnAsError': 'false', # TODO(maruel): Enable it.
                 'Detect64BitPortabilityProblems': 'false',
               },
             },
           }],
+          # TODO(darin): Unfortunately, some third_party code depends on base/
+          [ 'OS=="win" and component=="shared_library"', {
+            'msvs_disabled_warnings': [
+              4251,  # class 'std::xx' needs to have dll-interface.
+            ],
+          }],
           [ 'OS=="mac"', {
             'xcode_settings': {
               'GCC_TREAT_WARNINGS_AS_ERRORS': 'NO',
               'WARNING_CFLAGS!': ['-Wall', '-Wextra'],
             },
           }],
         ],
       }, {
         # In Chromium code, we define __STDC_FORMAT_MACROS in order to get the
         # C99 macros on Mac and Linux.
@@ skipping 962 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }