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/default_policy.h b/policy_manager/default_policy.h
index 63b674e..1eeb54b 100644
--- a/policy_manager/default_policy.h
+++ b/policy_manager/default_policy.h
@@ -20,7 +20,14 @@
   // Policy overrides.
   virtual EvalStatus UpdateCheckAllowed(EvaluationContext* ec, State* state,
                                         std::string* error,
-                                        bool* result) const {
+                                        bool* result) const override {
+    *result = true;
+    return EvalStatus::kSucceeded;
+  }
+
+  virtual EvalStatus UpdateDownloadAndApplyAllowed(
+      EvaluationContext* ec, State* state, std::string* error,
+      bool* result) const override {
     *result = true;
     return EvalStatus::kSucceeded;
   }