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 <[email protected]>
Tested-by: Alex Vakulenko <[email protected]>
Commit-Queue: Alex Vakulenko <[email protected]>
diff --git a/omaha_request_params_unittest.cc b/omaha_request_params_unittest.cc
index 01cf154..432eb6c 100644
--- a/omaha_request_params_unittest.cc
+++ b/omaha_request_params_unittest.cc
@@ -79,7 +79,7 @@
     machine_type.erase(newline_pos);
   return machine_type;
 }
-}  // namespace {}
+}  // namespace
 
 TEST_F(OmahaRequestParamsTest, SimpleTest) {
   ASSERT_TRUE(WriteFileString(