Basic underpinnings of the gyp equivalent of the Linux SHARED=1 build:...

sdch/sdch.gyp

 # Copyright (c) 2009 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'includes': [
     '../build/common.gypi',
   ],
   'targets': [
     {
       'target_name': 'sdch',
-      'type': 'static_library',
+      'type': '<(library)',
       'msvs_guid': 'F54ABC59-5C00-414A-A9BA-BAF26D1699F0',
       'sources': [
         'open-vcdiff/src/addrcache.cc',
         'open-vcdiff/src/adler32.c',
         'open-vcdiff/src/blockhash.cc',
         'open-vcdiff/src/blockhash.h',
         'open-vcdiff/src/checksum.h',
         'open-vcdiff/src/codetable.cc',
         'open-vcdiff/src/codetable.h',
         'open-vcdiff/src/compile_assert.h',
@@ skipping 31 matching lines @@
         ],
       },
       'conditions': [
         [ 'OS == "linux"', { 'include_dirs': [ 'linux' ] } ],
         [ 'OS == "mac"', { 'include_dirs': [ 'mac' ] } ],
         [ 'OS == "win"', { 'include_dirs': [ 'open-vcdiff/vsprojects' ] } ],
       ],
     },
   ],
 }