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/generic_variables_unittest.cc b/update_manager/generic_variables_unittest.cc
index 51ae4bd..bbf3996 100644
--- a/update_manager/generic_variables_unittest.cc
+++ b/update_manager/generic_variables_unittest.cc
@@ -70,7 +70,7 @@
 
 
 TEST_F(UmPollCopyVariableTest, UseCopyConstructorTest) {
-  // Ensures that CopyVariables indeed uses the copy contructor.
+  // Ensures that CopyVariables indeed uses the copy constructor.
   const CopyConstructorTestClass source;
   ASSERT_FALSE(source.copied_);