base: Simplify the construction of MD5Digest.

components/metrics/metrics_hashes.cc

 // Copyright 2014 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/metrics/metrics_hashes.h"
 
 #include "base/logging.h"
 #include "base/md5.h"
 #include "base/sys_byteorder.h"
 
@@ skipping 14 matching lines @@
 uint64 HashMetricName(const std::string& name) {
   // Create an MD5 hash of the given |name|, represented as a byte buffer
   // encoded as an std::string.
   base::MD5Context context;
   base::MD5Init(&context);
   base::MD5Update(&context, name);
 
   base::MD5Digest digest;
   base::MD5Final(&digest, &context);
 
-  std::string hash_str(reinterpret_cast<char*>(digest.a), arraysize(digest.a));
+  std::string hash_str(reinterpret_cast<char*>(digest), arraysize(digest));
   return HashToUInt64(hash_str);
 }
 
 }  // namespace metrics