Generate platform files under platform subdir.

Source/platform/blink_platform_tests.gyp

 #
 # Copyright (C) 2013 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
@@ skipping 77 matching lines @@
         '../wtf/wtf_tests.gyp:wtf_unittest_helpers',
         'blink_platform.gyp:blink_platform',
         'blink_platform.gyp:blink_common',
         '<(DEPTH)/skia/skia.gyp:skia',
         '<(DEPTH)/url/url.gyp:url_lib',
       ],
       'defines': [
         'INSIDE_BLINK',
       ],
       'include_dirs': [
-        '<(SHARED_INTERMEDIATE_DIR)/blink',
+        '<(blink_platform_output_dir)',
       ],
       'sources': [
         '<@(platform_test_files)',
       ],
       'conditions': [
         ['os_posix==1 and OS!="mac" and OS!="android" and OS!="ios" and use_allocator!="none"', {
           'dependencies': [
             '<(DEPTH)/base/base.gyp:base',
             '<(DEPTH)/base/allocator/allocator.gyp:allocator',
           ]
@@ skipping 47 matching lines @@
           'blink_platform_unittests',
         ],
         'variables': {
           'test_suite_name': 'blink_platform_unittests',
         },
         'includes': [ '../../../../build/apk_test.gypi' ],
       }],
     }],
   ],
 }