buffet: Use Transport::CreateDefault() to create curl http transport

Using chromeos::http::Transport::CreateDefault() instead of
explicitly creating chromeos::http::curl::Transport.

BUG=None
TEST=FEATURES=test emerge-link buffet

Change-Id: I2b7300f404d2cbeecc45960031eb266dea1afe35
Reviewed-on: https://chromium-review.googlesource.com/216476
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Reviewed-by: Christopher Wiley <wiley@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>

buffet/device_registration_info.cc

diff --git a/buffet/device_registration_info.cc b/buffet/device_registration_info.cc
index e3acea3..0368c83 100644
--- a/buffet/device_registration_info.cc
+++ b/buffet/device_registration_info.cc
@@ -11,7 +11,6 @@
 #include <base/json/json_writer.h>
 #include <base/values.h>
 #include <chromeos/data_encoding.h>
-#include <chromeos/http/http_transport_curl.h>
 #include <chromeos/http/http_utils.h>
 #include <chromeos/mime_utils.h>
 #include <chromeos/strings/string_utils.h>
@@ -143,7 +142,7 @@
 
 DeviceRegistrationInfo::DeviceRegistrationInfo(
     const std::shared_ptr<CommandManager>& command_manager)
-    : transport_(new chromeos::http::curl::Transport()),
+    : transport_(chromeos::http::Transport::CreateDefault()),
       // TODO(avakulenko): Figure out security implications of storing
       // this data unencrypted.
       storage_(new FileStorage(base::FilePath(kDeviceInfoFilePath))),