UpdateManager: rename UpdateCurrentConnectionAllowed into UpdateDownloadAllowed.

The signifies the *functional* nature of this policy request, instead of
dwelling on the low-level information it is evaluating.

BUG=chromium:389677
TEST=Unit tests.

Change-Id: I684ea13d4e89554b6a4d596666c18e2dbd609991
Reviewed-on: https://chromium-review.googlesource.com/206903
Tested-by: Gilad Arnold <garnold@chromium.org>
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
diff --git a/update_manager/default_policy.h b/update_manager/default_policy.h
index 6cdc19d..54bbe3e 100644
--- a/update_manager/default_policy.h
+++ b/update_manager/default_policy.h
@@ -47,7 +47,7 @@
     return EvalStatus::kSucceeded;
   }
 
-  virtual EvalStatus UpdateCurrentConnectionAllowed(
+  virtual EvalStatus UpdateDownloadAllowed(
       EvaluationContext* ec,
       State* state,
       std::string* error,