Enable some parts of base that were previously disabled in base_untrusted

base/base64.cc

 // Copyright (c) 2012 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 "base/base64.h"
 
+#include "base/compiler_specific.h"
+
+MSVC_PUSH_DISABLE_WARNING(4267);
 #include "third_party/modp_b64/modp_b64.h"
+MSVC_POP_WARNING();
 
 namespace base {
 
 bool Base64Encode(const StringPiece& input, std::string* output) {
   std::string temp;
   temp.resize(modp_b64_encode_len(input.size()));  // makes room for null byte
 
   // null terminates result since result is base64 text!
   int input_size = static_cast<int>(input.size());
 
@@ skipping 16 matching lines @@
   int output_size = modp_b64_decode(&(temp[0]), input.data(), input_size);
   if (output_size < 0)
     return false;
 
   temp.resize(output_size);
   output->swap(temp);
   return true;
 }
 
 }  // namespace base