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/fake_update_manager.h b/update_manager/fake_update_manager.h
index 0831b2e..f066df0 100644
--- a/update_manager/fake_update_manager.h
+++ b/update_manager/fake_update_manager.h
@@ -15,7 +15,7 @@
 class FakeUpdateManager : public UpdateManager {
  public:
   explicit FakeUpdateManager(chromeos_update_engine::ClockInterface* clock)
-      : UpdateManager(clock, new FakeState()) {
+      : UpdateManager(clock, base::TimeDelta::FromSeconds(5), new FakeState()) {
     // The FakeUpdateManager uses a DefaultPolicy.
     set_policy(new DefaultPolicy());
   }