PM: New (stub) policy for whether an update can be applied.

There's no implementation for this policy yet, and so it always returns
true.

BUG=chromium:358323
TEST=Unit tests.

Change-Id: Id3a0d13cf8c2e9061b800b114d8476c11f998df0
Reviewed-on: https://chromium-review.googlesource.com/197376
Reviewed-by: Gilad Arnold <garnold@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
Tested-by: Gilad Arnold <garnold@chromium.org>
diff --git a/policy_manager/chromeos_policy.cc b/policy_manager/chromeos_policy.cc
index cd10918..4a9f601 100644
--- a/policy_manager/chromeos_policy.cc
+++ b/policy_manager/chromeos_policy.cc
@@ -18,4 +18,13 @@
   return EvalStatus::kSucceeded;
 }
 
+EvalStatus ChromeOSPolicy::UpdateDownloadAndApplyAllowed(EvaluationContext* ec,
+                                                         State* state,
+                                                         string* error,
+                                                         bool* result) const {
+  // TODO(garnold): Write this policy implementation with the actual policy.
+  *result = true;
+  return EvalStatus::kSucceeded;
+}
+
 }  // namespace chromeos_policy_manager