AU: propagate a deadline form the update check response to Chrome.

Currently, this is done through the file system.

BUG=3284
TEST=unit tests

Change-Id: I0e579ef6ccd7832ca22a248e71f2689c27159056

TBR=resubmitting due to git issues
diff --git a/omaha_request_action.cc b/omaha_request_action.cc
index cb9cd63..ecee25e 100644
--- a/omaha_request_action.cc
+++ b/omaha_request_action.cc
@@ -412,6 +412,7 @@
   output_object.prompt = XmlGetProperty(updatecheck_node, "Prompt") == "true";
   output_object.is_delta =
       XmlGetProperty(updatecheck_node, "IsDelta") == "true";
+  output_object.deadline = XmlGetProperty(updatecheck_node, "deadline");
   SetOutputObject(output_object);
 }