Support in update_engine for the crosh autest "-scheduled" option.

This is needed to enable manual testing of scattering feature on
MP-signed images.

BUG=chromium-os:32289
TEST=update_engine_client works as expected on zgb when passing
     autest and autest-scatter to omaha_url.
Change-Id: Ib3d3e70f2e87632b6a61c7e5cd45791210c12c99
Reviewed-on: https://gerrit.chromium.org/gerrit/27005
Reviewed-by: Gilad Arnold <garnold@chromium.org>
Reviewed-by: Jay Srinivasan <jaysri@chromium.org>
Tested-by: Jay Srinivasan <jaysri@chromium.org>
Commit-Ready: Jay Srinivasan <jaysri@chromium.org>
diff --git a/update_attempter.cc b/update_attempter.cc
index 68c1417..8b77a95 100644
--- a/update_attempter.cc
+++ b/update_attempter.cc
@@ -456,7 +456,8 @@
 }
 
 void UpdateAttempter::CheckForUpdate(const string& app_version,
-                                     const string& omaha_url) {
+                                     const string& omaha_url,
+                                     bool is_user_initiated) {
   LOG(INFO) << "New update check requested";
 
   if (status_ != UPDATE_STATUS_IDLE) {
@@ -477,7 +478,7 @@
 
   // Passing true for is_user_initiated to indicate that this
   // is not a scheduled update check.
-  Update(app_version, omaha_url, true, true, is_test, true);
+  Update(app_version, omaha_url, true, true, is_test, is_user_initiated);
 }
 
 bool UpdateAttempter::RebootIfNeeded() {