network_time_tracker: add temporary time protocol.

components/client_update_protocol/ecdsa.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/client_update_protocol/ecdsa.h"
 
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 82 matching lines @@
 std::unique_ptr<Ecdsa> Ecdsa::Create(int key_version,
                                      const base::StringPiece& public_key) {
   DCHECK_GT(key_version, 0);
   DCHECK(!public_key.empty());
 
   return base::WrapUnique(new Ecdsa(key_version, public_key));
 }
 
 void Ecdsa::SignRequest(const base::StringPiece& request_body,
                         std::string* query_params) {
-  DCHECK(!request_body.empty());
   DCHECK(query_params);
 
   // Generate a random nonce to use for freshness, build the cup2key query
   // string, and compute the SHA-256 hash of the request body. Set these
   // two pieces of data aside to use during ValidateResponse().
   uint32_t nonce = 0;
   crypto::RandBytes(&nonce, sizeof(nonce));
   request_query_cup2key_ = base::StringPrintf("%d:%u", pub_key_version_, nonce);
   request_hash_ = SHA256HashStr(request_body);
 
@@ skipping 64 matching lines @@
   // * The signature was modified
   // * The buffer that the server signed does not match the buffer that the
   //   client assembled -- implying that either request body or response body
   //   was modified, or a different nonce value was used.
   verifier.VerifyUpdate(&signed_message_hash.front(),
                         static_cast<int>(signed_message_hash.size()));
   return verifier.VerifyFinal();
 }
 
 }  // namespace client_update_protocol