exernalize imagefactory guard

gyp/skia_for_android_framework_defines.gypi

 # Copyright 2014 Google Inc.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # This file is included by chrome's skia/skia_common.gypi, and is intended to
 # augment the skia flags that are set there.
 
 {
   'variables': {
 
     # These flags will be defined in the android framework.
     #
     # If these become 'permanent', they should be moved into common_variables.gypi
     #
     'skia_for_android_framework_defines': [
       'SK_SUPPORT_LEGACY_UNBALANCED_PIXELREF_LOCKCOUNT',
       # Needed until we fix https://bug.skia.org/2440 .
       'SK_SUPPORT_LEGACY_CLIPTOLAYERFLAG',
       'SK_SUPPORT_LEGACY_COLORFILTER_PTR',
       'SK_IGNORE_LINEONLY_AA_CONVEX_PATH_OPTS',
       'SK_SUPPORT_LEGACY_MINOR_EFFECT_PTR',
       'SK_SUPPORT_LEGACY_GRADIENT_DITHERING',
       'SK_SUPPORT_LEGACY_DRAWFILTER',
       'SK_SUPPORT_LEGACY_CREATESHADER_PTR',
       'SK_SUPPORT_LEGACY_PATHEFFECT_PTR',
       'SK_SUPPORT_LEGACY_NEW_SURFACE_API',
       'SK_SUPPORT_LEGACY_PICTURE_PTR',
       'SK_SUPPORT_LEGACY_MASKFILTER_PTR',
+      'SK_SUPPORT_LEGACY_IMAGEFACTORY',
       'SK_SUPPORT_LEGACY_XFERMODE_PTR',
     ],
   },
 }