Add enable_dsyms=true option when building CronetChromeWebView framework.

ios/web_view/tools/build.py

 #!/usr/bin/python
 # Copyright 2017 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.
 
 """
 Builds and packages CronetChromeWebView.framework.
 """
 
 import argparse
@@ skipping 34 matching lines @@
     build_config_gn_args = 'is_debug=true'
   else:
     build_config_gn_args = ('is_debug=false enable_stripping=true '
                             'is_official_build=true')
 
   build_dir = os.path.join("out", target_dir_name(build_config, target_device))
   gn_args = ('target_os="ios" enable_websockets=false '
             'is_component_build=false use_xcode_clang=true '
             'disable_file_support=true disable_ftp_support=true '
             'disable_brotli_filter=true ios_enable_code_signing=false '
+            'enable_dsyms=true '
             'target_cpu="%s" additional_target_cpus = ["%s"] %s %s' %
             (target_cpu, additional_cpu, build_config_gn_args,
              extra_gn_options))
 
   gn_command = 'gn gen %s --args=\'%s\'' % (build_dir, gn_args)
   print gn_command
   gn_result = os.system(gn_command)
   if gn_result != 0:
     return gn_result
 
@@ skipping 110 matching lines @@
     print >>sys.stderr, 'The output directory already exists: ' + out_dir
     return 1
 
   gn_options = '' if options.no_goma else 'use_goma=true'
 
   return package_all_frameworks(out_dir, gn_options)
 
 
 if __name__ == '__main__':
   sys.exit(main())