Test Web Proxy Auto Config

Perform a DHCP negotiation where the server provides a Web Proxy
Auto Config option.  Test to make sure that the shill IPConfig
contains this value.

CQ-DEPEND=CL:60015
BUG=chromium:253915
TEST=This is a test.

Change-Id: Iae1d23f69e83c51b0cfc8afbc75cc3aec7fdd4dc
Reviewed-on: https://gerrit.chromium.org/gerrit/60020
Reviewed-by: Paul Stewart <[email protected]>
Tested-by: Paul Stewart <[email protected]>
Commit-Queue: Paul Stewart <[email protected]>
diff --git a/client/cros/dhcp_packet.py b/client/cros/dhcp_packet.py
index e218cf9..844d7d0 100644
--- a/client/cros/dhcp_packet.py
+++ b/client/cros/dhcp_packet.py
@@ -345,6 +345,7 @@
 OPTION_DNS_DOMAIN_SEARCH_LIST = DomainListOption("domain_search_list", 119)
 OPTION_CLASSLESS_STATIC_ROUTES = ClasslessStaticRoutesOption(
         "classless_static_routes", 121)
+OPTION_WEB_PROXY_AUTO_DISCOVERY = RawOption("wpad", 252)
 
 # Unlike every other option, which are tuples like:
 # <number, length in bytes, data>, the pad and end options are just
@@ -460,6 +461,7 @@
         OPTION_BOOTFILE_NAME,
         OPTION_DNS_DOMAIN_SEARCH_LIST,
         OPTION_CLASSLESS_STATIC_ROUTES,
+        OPTION_WEB_PROXY_AUTO_DISCOVERY,
         ]
 
 def get_dhcp_option_by_number(number):