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>
diff --git a/certificate_checker.cc b/certificate_checker.cc
index 02b5661..a774900 100644
--- a/certificate_checker.cc
+++ b/certificate_checker.cc
@@ -29,7 +29,7 @@
 static const char* kReportToSendKey[2] =
     {kPrefsCertificateReportToSendUpdate,
      kPrefsCertificateReportToSendDownload};
-}  // namespace {}
+}  // namespace
 
 bool OpenSSLWrapper::GetCertificateDigest(X509_STORE_CTX* x509_ctx,
                                           int* out_depth,