[Cronet] Use gn desc deps to find third_party licenses.

components/cronet/tools/cr_cronet.py

Index: components/cronet/tools/cr_cronet.py
diff --git a/components/cronet/tools/cr_cronet.py b/components/cronet/tools/cr_cronet.py
index c852077666cf9bd2b56935a74bf1708c49871161..3fbd5c01bf34c53513176a058ccef579af1932f7 100755
--- a/components/cronet/tools/cr_cronet.py
+++ b/components/cronet/tools/cr_cronet.py
@@ -77,21 +77,24 @@ def main():
   if is_os:
     target_os = 'ios'
     test_target = 'cronet_test'
+    gn_args = 'target_cpu = "x64" '
     out_dir_suffix = '-iphonesimulator'
     if options.iphoneos:
+      gn_args = 'target_cpu = "arm64" '
       out_dir_suffix = '-iphoneos'
   else:
     target_os = 'android'
     test_target = 'cronet_test_instrumentation_apk'
+    gn_args = 'use_errorprone_java_compiler=true '
     out_dir_suffix = ''
 
   gyp_defines = 'GYP_DEFINES="OS=' + target_os + ' enable_websockets=0 '+ \
       'disable_file_support=1 disable_ftp_support=1 '+ \
       'enable_errorprone=1 use_platform_icu_alternatives=1 ' + \
       'disable_brotli_filter=1"'
-  gn_args = 'target_os="' + target_os + '" enable_websockets=false '+ \
+  gn_args += 'target_os="' + target_os + '" enable_websockets=false '+ \
       'disable_file_support=true disable_ftp_support=true '+ \
-      'use_errorprone_java_compiler=true use_platform_icu_alternatives=true '+ \
+      'use_platform_icu_alternatives=true '+ \
       'disable_brotli_filter=true'
 
   extra_options = ' '.join(extra_options_list)