Convert from using env['PLATFORM'] directly to using the more flexible...

base/gfx/base_gfx.scons

 # Copyright (c) 2006-2008 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.
 
 __doc__ = """
 Configuration for building base_gfx.lib / libbase_gfx.a.
 """
 
 Import('env')
 
 env = env.Clone()
 
 env.ApplySConscript([
     '$ICU38_DIR/using_icu38.scons',
     '$LIBPNG_DIR/using_libpng.scons',
     '$SKIA_DIR/using_skia.scons',
     '$ZLIB_DIR/using_zlib.scons',
 ])
 
-if env['PLATFORM'] == 'win32':
+if env.Bit('windows'):
   env.Prepend(
       CCFLAGS = [
           '/WX',
       ],
   )
 
 input_files = [
     'gdi_util.cc',
     'native_theme.cc',
     'png_decoder.cc',
     'png_encoder.cc',
     'point.cc',
     'rect.cc',
     'size.cc',
 ]
 
-if env['PLATFORM'] in ('posix', 'darwin'):
+if env.Bit('posix'):
   # Remove files that still need to be ported from the input_files list.
   # TODO(port): delete files from this list as they get ported.
   to_be_ported_files = [
       'gdi_util.cc',
       'native_theme.cc',
   ]
   for remove in to_be_ported_files:
     input_files.remove(remove)
 
-if env['PLATFORM'] == 'win32':
+if env.Bit('windows'):
   input_files.extend([
   ])
-elif env['PLATFORM'] == 'posix':
+elif env.Bit('linux'):
   input_files.extend([
   ])
 
 env.ChromeStaticLibrary('base_gfx', input_files)