Allow to set the network used for an update attempt.
When triggering an update attempt in Android, we can force all the
traffic to go through a given network by passing a NETWORK_ID=<id>
in the extra key-value pair field.
Bug: 29921093
TEST=Called update_engine_client passing NETWORK_ID.
Change-Id: I13becdd133cccc912b542d48061fcfe9f566099a
diff --git a/common/constants.h b/common/constants.h
index 649034e..ab66921 100644
--- a/common/constants.h
+++ b/common/constants.h
@@ -94,6 +94,7 @@
extern const char kPayloadPropertyAuthorization[];
extern const char kPayloadPropertyUserAgent[];
extern const char kPayloadPropertyPowerwash[];
+extern const char kPayloadPropertyNetworkId[];
// A download source is any combination of protocol and server (that's of
// interest to us when looking at UMA metrics) using which we may download