update_engine: Use clock and fake clock from SystemState

No need to pass clock and fake clock anywhere anymore. This CL makes it
to just use those objects available from SystemState and
FakeSystemState.

BUG=b:171829801
TEST=cros_workon_make --board reef --test update_engine

Change-Id: I9a3cf6dd2057620c11b862d3317b83489c76f3ca
Reviewed-on: https://chromium-review.googlesource.com/c/aosp/platform/system/update_engine/+/2546625
Tested-by: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Jae Hoon Kim <kimjae@chromium.org>
Commit-Queue: Jae Hoon Kim <kimjae@chromium.org>
diff --git a/update_manager/update_manager.cc b/update_manager/update_manager.cc
index 2974d7d..dbb6b33 100644
--- a/update_manager/update_manager.cc
+++ b/update_manager/update_manager.cc
@@ -19,14 +19,11 @@
 
 namespace chromeos_update_manager {
 
-UpdateManager::UpdateManager(chromeos_update_engine::ClockInterface* clock,
-                             base::TimeDelta evaluation_timeout,
+UpdateManager::UpdateManager(base::TimeDelta evaluation_timeout,
                              base::TimeDelta expiration_timeout,
                              State* state)
     : policy_(GetSystemPolicy()),
-      default_policy_(clock),
       state_(state),
-      clock_(clock),
       evaluation_timeout_(evaluation_timeout),
       expiration_timeout_(expiration_timeout),
       weak_ptr_factory_(this) {}