Generate bench/Android.mk from gyp.

gyp/common_conditions.gypi

 # conditions used in both common.gypi and skia.gyp in chromium
 #
 {
   'defines': [
     'SK_ALLOW_STATIC_GLOBAL_INITIALIZERS=<(skia_static_initializers)',
     'SK_SUPPORT_GPU=<(skia_gpu)',
     'SK_SUPPORT_OPENCL=<(skia_opencl)',
     'SK_FORCE_DISTANCEFIELD_FONTS=<(skia_force_distancefield_fonts)',
   ],
   'conditions' : [
@@ skipping 621 matching lines @@
     }],
 
     [ 'skia_moz2d', {
       'defines': [
         'SK_SUPPORT_LEGACY_LAYERRASTERIZER_API=1',
         'SK_SUPPORT_LEGACY_COMPATIBLEDEVICE_CONFIG=1',
         'SK_SUPPORT_LEGACY_GETTOTALCLIP=1',
       ],
     }],
 
+    [ 'skia_build_json_writer', {
+      'defines': [
+        'SK_BUILD_JSON_WRITER',
+      ]
+    }],
+
   ], # end 'conditions'
   # The Xcode SYMROOT must be at the root. See build/common.gypi in chromium for more details
   'xcode_settings': {
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }