update_engine: fixed remaining linter and some spelling errors

Fixed remaining errors from cpplint as well as some spelling errors
mostly in comments.

BUG=None
TEST=FEATURES=test emerge-link update_engine

Change-Id: I484988ab846ac5a3c68c016ddccfb247f225ec27
Reviewed-on: https://chromium-review.googlesource.com/208897
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
diff --git a/update_manager/policy.h b/update_manager/policy.h
index 64869c0..df21fde 100644
--- a/update_manager/policy.h
+++ b/update_manager/policy.h
@@ -162,7 +162,7 @@
   // that need to be persisted has changed, returns
   // EvalStatus::kAskMeAgainLater. Arguments include an |interactive| flag that
   // tells whether the update is user initiated, and an |update_state| that
-  // encapsulates data pertaining to the currnet ongoing update process.
+  // encapsulates data pertaining to the current ongoing update process.
   virtual EvalStatus UpdateCanStart(
       EvaluationContext* ec,
       State* state,