UM: Make the evaluation timeout configurable.

This allows the client to construct the UpdateManager with a custom
evaluation timeout for sync policy requests, which is in turn being
passed to each EvaluationContext instance used for sync policy
evaluation.

BUG=chromium:363790
TEST=Unit tests.

Change-Id: I5a6ec02a3ca2a2c611276eacbcda6aac8304e929
Reviewed-on: https://chromium-review.googlesource.com/204687
Reviewed-by: Gilad Arnold <garnold@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
Tested-by: Gilad Arnold <garnold@chromium.org>
diff --git a/update_manager/update_manager.cc b/update_manager/update_manager.cc
index d3281fd..d6ffcee 100644
--- a/update_manager/update_manager.cc
+++ b/update_manager/update_manager.cc
@@ -10,8 +10,8 @@
 namespace chromeos_update_manager {
 
 UpdateManager::UpdateManager(chromeos_update_engine::ClockInterface* clock,
-                             State* state)
-      : state_(state), clock_(clock) {
+                             base::TimeDelta evaluation_timeout, State* state)
+      : state_(state), clock_(clock), evaluation_timeout_(evaluation_timeout) {
   // TODO(deymo): Make it possible to replace this policy with a different
   // implementation with a build-time flag.
   policy_.reset(new ChromeOSPolicy());