Reduce number of resume attempts and delay between attempts.

This reduces the number of resume attempts from 20 to 3 (total
4 attempts), and the delay between a failure and the subsequent attempt
from 60 to 20 seconds.  In total, the delay induced due to resume
attempts will not exceed 1 minute.  This appears long enough to overcome
transient connectivity issues such as a user moving between access
points, a temporary Ethernet cable disconnect, or a switch restarting.
It is necessary for reducing the amount of time a user needs to wait in
the case of interrupted network connectivity during OOBE update.

This requires a corresponding fix to unittests, as the assumption on the
number of retries has changed.

BUG=chrome-os-partner:7961
TEST=Passed unittests; verifying OOBE behavior pending at test lab.

Change-Id: I669ac6e2a1264c1d154b23a06c66763f155ab946
Reviewed-on: https://gerrit.chromium.org/gerrit/15639
Reviewed-by: Gilad Arnold <garnold@chromium.org>
Tested-by: Gilad Arnold <garnold@chromium.org>
Commit-Ready: Gilad Arnold <garnold@chromium.org>
diff --git a/libcurl_http_fetcher.h b/libcurl_http_fetcher.h
index ff8589b..e87c678 100644
--- a/libcurl_http_fetcher.h
+++ b/libcurl_http_fetcher.h
@@ -36,7 +36,7 @@
         download_length_(0),
         resume_offset_(0),
         retry_count_(0),
-        retry_seconds_(60),
+        retry_seconds_(20),
         no_network_retry_count_(0),
         no_network_max_retries_(0),
         idle_seconds_(1),