buffet: change error namespace conventions to align with error_codes.h

Now all error codes will be in top-level buffet::errors namespace
with specific domain as a sub-namespace, for example:
buffet::errors::commands for errors about GCD command schema.

BUG=None
TEST=USE=buffet P2_TEST_FILTER="buffet::*" FEATURES=test emerge-link platform2

Change-Id: I905d0d63fbba35a30d13ae925181c443b5449d57
Reviewed-on: https://chromium-review.googlesource.com/209249
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Reviewed-by: Christopher Wiley <wiley@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
diff --git a/buffet/commands/schema_utils.cc b/buffet/commands/schema_utils.cc
index 3c6ae57..cef5030 100644
--- a/buffet/commands/schema_utils.cc
+++ b/buffet/commands/schema_utils.cc
@@ -22,8 +22,8 @@
                             ErrorPtr* error) {
   std::string value_as_string;
   base::JSONWriter::Write(value_in, &value_as_string);
-  Error::AddToPrintf(error, commands::errors::kDomain,
-                     commands::errors::kTypeMismatch,
+  Error::AddToPrintf(error, errors::commands::kDomain,
+                     errors::commands::kTypeMismatch,
                      "Unable to convert value %s into %s",
                      value_as_string.c_str(), expected_type.c_str());
 }
@@ -40,8 +40,8 @@
 }
 
 bool ErrorMissingProperty(ErrorPtr* error, const char* param_name) {
-  Error::AddToPrintf(error, commands::errors::kDomain,
-                     commands::errors::kPropertyMissing,
+  Error::AddToPrintf(error, errors::commands::kDomain,
+                     errors::commands::kPropertyMissing,
                      "Required parameter missing: %s", param_name);
   return false;
 }
@@ -142,8 +142,8 @@
     std::string key = iter.key();
     if (keys_processed.find(key) == keys_processed.end() &&
         !object_schema->GetExtraPropertiesAllowed()) {
-      Error::AddToPrintf(error, commands::errors::kDomain,
-                         commands::errors::kUnknownProperty,
+      Error::AddToPrintf(error, errors::commands::kDomain,
+                         errors::commands::kUnknownProperty,
                          "Unrecognized parameter '%s'", key.c_str());
       return false;
     }
@@ -155,8 +155,8 @@
     const PropType* prop_type = pair.second->GetPropType();
     CHECK(prop_type) << "Value property type must be available";
     if (!prop_type->ValidateConstraints(*pair.second, error)) {
-      Error::AddToPrintf(error, commands::errors::kDomain,
-                         commands::errors::kInvalidPropValue,
+      Error::AddToPrintf(error, errors::commands::kDomain,
+                         errors::commands::kInvalidPropValue,
                          "Invalid parameter value for property '%s'",
                          pair.first.c_str());
       return false;