Update licence generation script after GYP->GN migration.

tools-webrtc/ios/build_ios_libs.py

 #!/usr/bin/env python
 
 # Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
@@ skipping 186 matching lines @@
                                'WebRTC')
       lib_dsym_paths = [os.path.join(path, dsym_path) for path in lib_paths]
       out_dsym_path = os.path.join(args.output_dir, dsym_path)
       try:
         os.remove(out_dsym_path)
       except OSError:
         pass
       cmd = ['lipo'] + lib_dsym_paths + ['-create', '-output', out_dsym_path]
       _RunCommand(cmd)
 
+    # Generate the license file.
+    license_script_path = os.path.join(SCRIPT_DIR, 'generate_licenses.py')
+    ninja_dirs = [os.path.join(args.output_dir, arch + '_libs')
+                  for arch in architectures]
+    gn_target_full_name = '//webrtc/sdk:rtc_sdk_framework_objc'
+    cmd = [sys.executable, license_script_path, gn_target_full_name,
+           os.path.join(args.output_dir, SDK_FRAMEWORK_NAME)] + ninja_dirs
+    _RunCommand(cmd)
+
     # Modify the version number.
     # Format should be <Branch cut MXX>.<Hotfix #>.<Rev #>.
     # e.g. 55.0.14986 means branch cut 55, no hotfixes, and revision 14986.
     infoplist_path = os.path.join(args.output_dir, SDK_FRAMEWORK_NAME,
                                   'Info.plist')
     cmd = ['PlistBuddy', '-c',
            'Print :CFBundleShortVersionString', infoplist_path]
     major_minor = subprocess.check_output(cmd).strip()
     version_number = '%s.%s' % (major_minor, args.revision)
     logging.info('Substituting revision number: %s', version_number)
     cmd = ['PlistBuddy', '-c',
            'Set :CFBundleVersion ' + version_number, infoplist_path]
     _RunCommand(cmd)
     _RunCommand(['plutil', '-convert', 'binary1', infoplist_path])
 
   logging.info('Done.')
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())