When persisting UMA logs to disk, cap log size based on both the XML and protocol buffer logs.

chrome/browser/metrics/metrics_log_serializer.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 "chrome/browser/metrics/metrics_log_serializer.h"
 
 #include "base/base64.h"
 #include "base/md5.h"
 #include "base/metrics/histogram.h"
 #include "chrome/browser/browser_process.h"
@@ skipping 137 matching lines @@
     return;
 
   size_t start = 0;
   // If there are too many logs, keep the most recent logs up to the length
   // limit, and at least to the minimum number of bytes.
   if (local_list.size() > list_length_limit) {
     start = local_list.size();
     size_t bytes_used = 0;
     for (std::vector<MetricsLogManager::SerializedLog>::const_reverse_iterator
          it = local_list.rbegin(); it != local_list.rend(); ++it) {
-      // TODO(isherman): Always uses XML length so both formats of a given log
-      // will be saved; switch to proto once that's the primary format.
-      size_t log_size = it->xml.length();
+      size_t log_size = it->length();
       if (bytes_used >= byte_limit &&
           (local_list.size() - start) >= list_length_limit)
         break;
       bytes_used += log_size;
       --start;
     }
   }
   DCHECK_LT(start, local_list.size());
   if (start >= local_list.size())
     return;
@@ skipping 93 matching lines @@
   if (!valid) {
     local_list->clear();
     return MakeRecallStatusHistogram(CHECKSUM_STRING_CORRUPTION, is_xml);
   }
   if (recovered_md5 != base::MD5DigestToBase16(digest)) {
     local_list->clear();
     return MakeRecallStatusHistogram(CHECKSUM_CORRUPTION, is_xml);
   }
   return MakeRecallStatusHistogram(RECALL_SUCCESS, is_xml);
 }