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/delta_performer.cc b/delta_performer.cc
index ef66af0..2008536 100644
--- a/delta_performer.cc
+++ b/delta_performer.cc
@@ -73,7 +73,7 @@
   return true;
 }
 
-}  // namespace {}
+}  // namespace
 
 
 // Computes the ratio of |part| and |total|, scaled to |norm|, using integer
@@ -278,7 +278,7 @@
     LogPartitionInfoHash(manifest.new_rootfs_info(), "new_rootfs_info");
 }
 
-}  // namespace {}
+}  // namespace
 
 uint64_t DeltaPerformer::GetVersionOffset() {
   // Manifest size is stored right after the magic string and the version.