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_unittest.cc b/update_manager/update_manager_unittest.cc
index fa6f9dd..640fbb3 100644
--- a/update_manager/update_manager_unittest.cc
+++ b/update_manager/update_manager_unittest.cc
@@ -58,7 +58,8 @@
  protected:
   virtual void SetUp() {
     fake_state_ = new FakeState();
-    umut_.reset(new UpdateManager(&fake_clock_, fake_state_));
+    umut_.reset(new UpdateManager(&fake_clock_, TimeDelta::FromSeconds(5),
+                                  fake_state_));
   }
 
   FakeState* fake_state_;  // Owned by the umut_.