Keep only base/extractor.[cc|h].

core/build.scons

-# Copyright 2009 Google Inc.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#      http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-# ========================================================================
-
-Import('env')
-
-local_env = env.Clone()
-
-inputs = [
-    'core.cc',
-    'core_metrics.cc',
-    'crash_handler.cc',
-    'google_update_core.cc',
-    'scheduler.cc',
-    'system_monitor.cc',
-    ]
-
-local_env['CPPPATH'] += [
-    '$MAIN_DIR/third_party/breakpad/src/',
-
-    # Need to look in output dir to find .h files generated by midl compiler.
-    # This also allows Hammer to understand dependencies between this subdir
-    # and the .idl files in the goopdate folder.
-    '$OBJ_ROOT',
-    ]
-
-local_env.ComponentStaticLibrary('core', inputs)