buffet: Remove 'chromeos' namespace and move everything to buffet NS

As discussed, moved all the classes out of chromeos namespace into
'buffet.

Also fixed a number of cpplint's warnings.

BUG=None
TEST=Everything still compiles and unit tests succeed.

Change-Id: Ide864acb2504627404966727f66d353af60e531d
Reviewed-on: https://chromium-review.googlesource.com/198971
Reviewed-by: Christopher Wiley <wiley@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
diff --git a/buffet/buffet_client.cc b/buffet/buffet_client.cc
index 16bbbb2..cec73e1 100644
--- a/buffet/buffet_client.cc
+++ b/buffet/buffet_client.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include <iostream>
+#include <iostream>  // NOLINT(readability/streams)
 #include <string>
 #include <sysexits.h>
 
@@ -130,7 +130,7 @@
     std::map<std::string, std::shared_ptr<base::Value>> params;
 
     if (!args.empty()) {
-      auto key_values = chromeos::data_encoding::WebParamsDecode(args.front());
+      auto key_values = buffet::data_encoding::WebParamsDecode(args.front());
       for (auto&& pair : key_values) {
         params.insert(std::make_pair(
           pair.first, std::shared_ptr<base::Value>(