update_engine: fixed warnings from cpplint

Fixed all the cpplint warnings in update engine.

BUG=None
TEST=Unit tests still pass.

Change-Id: I285ae858eec8abe0b26ff203b99a42a200ceb71c
Reviewed-on: https://chromium-review.googlesource.com/204027
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>

test_utils.cc

diff --git a/test_utils.cc b/test_utils.cc
index 7e03ef1..b452ca3 100644
--- a/test_utils.cc
+++ b/test_utils.cc
@@ -301,7 +301,7 @@
 
 ScopedLoopMounter::ScopedLoopMounter(const string& file_path,
                                      string* mnt_path,
-                                     unsigned long flags) {
+                                     unsigned long flags) {  // NOLINT - long
   EXPECT_TRUE(utils::MakeTempDirectory("mnt.XXXXXX", mnt_path));
   dir_remover_.reset(new ScopedDirRemover(*mnt_path));