miniz support in SkFlate / PDF

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_DISTANCE_FIELD_TEXT=<(skia_force_distance_field_text)',
   ],
   'conditions' : [
@@ skipping 21 matching lines @@
       'cflags': [
         '-msse2',
         '-mfpmath=sse',
       ],
     }],
 
     [ 'skia_os == "win"',
       {
         'defines': [
           'SK_BUILD_FOR_WIN32',
-          'SK_NO_FLATE',  # Too much of a pain to set up zlib on our bots.
           '_CRT_SECURE_NO_WARNINGS',
           'GR_GL_FUNCTION_TYPE=__stdcall',
         ],
         'msvs_disabled_warnings': [
             4275,  # An exported class was derived from a class that was not exported
             4345,  # This is an FYI about a behavior change from long ago. Chrome stifles it too.
             4355,  # 'this' used in base member initializer list. Off by default in newer compilers.
         ],
         'msvs_cygwin_shell': 0,
         'msvs_settings': {
@@ skipping 607 matching lines @@
         # add flags here (e.g. SK_SUPPORT_LEGACY_...) needed by moz2d
       ],
     }],
 
   ], # end 'conditions'
   # The Xcode SYMROOT must be at the root. See build/common.gypi in chromium for more details
   'xcode_settings': {
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }