shill: Fix most of warnings from cpplint

Fix most cpplinter's warnings. On a few occasisions, the warnings
produced were false-positives, so added explicit // NOLINT comment
overrides.

There were a few instances of disallowed non-const reference usage
(reported as runtime/reference error by cpplint) for
"DBus::Error &error" which should potentially be changed
to pointers to comply with C++ coding style but I will let Shill
owners do that since there is quite a few of those and the
change isn't brain-dead simple...

BUG=None
TEST=platform2 still compiles and all unit tests pass.

Change-Id: Ic2e31896aa13d20eeb1a85dee74f3db8cccfde2e
Reviewed-on: https://chromium-review.googlesource.com/204164
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Reviewed-by: mukesh agrawal <quiche@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
diff --git a/crypto_des_cbc_unittest.cc b/crypto_des_cbc_unittest.cc
index 2998fd6..4937aa2 100644
--- a/crypto_des_cbc_unittest.cc
+++ b/crypto_des_cbc_unittest.cc
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include <string>
+
 #include <base/file_util.h>
 #include <base/files/scoped_temp_dir.h>
 #include <gtest/gtest.h>
@@ -26,7 +28,7 @@
 const char kCipherText[] = "02:MbxzeBqK3HVeS3xfjyhbe47Xx+szYgOp";
 const char kPlainVersion1[] = "This is a test!";
 const char kCipherVersion1[] = "bKlHDISdHMFfmfgBTT5I0w==";
-}  // namespace {}
+}  // namespace
 
 class CryptoDESCBCTest : public Test {
  public: