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/update_manager-inl.h b/update_manager/update_manager-inl.h
index b5d3651..982ec93 100644
--- a/update_manager/update_manager-inl.h
+++ b/update_manager/update_manager-inl.h
@@ -105,7 +105,7 @@
     R* result, ActualArgs... args) {
   scoped_refptr<EvaluationContext> ec(
       new EvaluationContext(clock_, evaluation_timeout_));
-  // A PolicyRequest allways consists on a single evaluation on a new
+  // A PolicyRequest always consists on a single evaluation on a new
   // EvaluationContext.
   // IMPORTANT: To ensure that ActualArgs can be converted to ExpectedArgs, we
   // explicitly instantiate EvaluatePolicy with the latter in lieu of the