Add define of SK_ENABLE_VK_LAYERS to gn build

infra/bots/recipe_modules/flavor/gn_android_flavor.py

 # Copyright 2016 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.
 
 import default_flavor
 import subprocess
 
 # Data should go under in _data_dir, which may be preserved across runs.
 _data_dir = '/sdcard/revenge_of_the_skiabot/'
 # Executables go under _bin_dir, which, well, allows executable files.
@@ skipping 45 matching lines @@
     quote = lambda x: '"%s"' % x
     args = {
         'ndk': quote(self.m.vars.slave_dir.join(ndk_asset)),
         'target_cpu': quote(target_arch),
     }
 
     if configuration != 'Debug':
       args['is_debug'] = 'false'
     if 'Vulkan' in extra_config:
       args['ndk_api'] = 24
+      args['skia_enable_vulkan_debug_layers'] = 'false'
     if 'FrameworkDefs' in extra_config:
       args['skia_enable_android_framework_defines'] = 'true'
 
     gn_args = ' '.join('%s=%s' % (k,v) for (k,v) in sorted(args.iteritems()))
 
     self._run('fetch-gn', self.m.vars.skia_dir.join('bin', 'fetch-gn'),
               infra_step=True)
     self._run('gn gen', 'gn', 'gen', self.out_dir, '--args=' + gn_args)
     self._run('ninja', 'ninja', '-C', self.out_dir)
 
@@ skipping 79 matching lines @@
   def read_file_on_device(self, path):
     return self._adb('read %s' % path,
                      'shell', 'cat', path, stdout=self.m.raw_io.output()).stdout
 
   def remove_file_on_device(self, path):
     self._adb('rm %s' % path, 'shell', 'rm', '-f', path)
 
   def create_clean_device_dir(self, path):
     self._adb('rm %s' % path, 'shell', 'rm', '-rf', path)
     self._adb('mkdir %s' % path, 'shell', 'mkdir', '-p', path)