Simple Cache: Add two optional stream 2 histograms

net/disk_cache/simple/simple_entry_impl.cc

 // Copyright (c) 2013 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 "net/disk_cache/simple/simple_entry_impl.h"
 
 #include <algorithm>
 #include <cstring>
 #include <vector>
 
@@ skipping 1278 matching lines @@
       SimpleEntryStat(base::Time::Now(), last_modified_, data_size_));
   RecordReadResult(cache_type_, READ_RESULT_SUCCESS);
   return buf_len;
 }
 
 int SimpleEntryImpl::SetStream0Data(net::IOBuffer* buf,
                                     int offset,
                                     int buf_len,
                                     bool truncate) {
   // Currently, stream 0 is only used for HTTP headers, and always writes them
-  // with a single, truncating write.  Detect these writes and record the size
-  // changes of the headers.  Also, support writes to stream 0 that have
+  // with a single, truncating write. Detect these writes and record the size
+  // changes of the headers. Also, support writes to stream 0 that have
   // different access patterns, as required by the API contract.
   // All other clients of the Simple Cache are encouraged to use stream 1.
   have_written_[0] = true;
   int data_size = GetDataSize(0);
   if (offset == 0 && truncate) {
     RecordHeaderSizeChange(cache_type_, data_size, buf_len);
     stream_0_data_->SetCapacity(buf_len);
     memcpy(stream_0_data_->data(), buf->data(), buf_len);
     data_size_[0] = buf_len;
   } else {
@@ skipping 36 matching lines @@
     }
     crc32s_end_offset_[stream_index] = offset + length;
   } else if (offset < crc32s_end_offset_[stream_index]) {
     // If a range for which the crc32 was already computed is rewritten, the
     // computation of the crc32 need to start from 0 again.
     crc32s_end_offset_[stream_index] = 0;
   }
 }
 
 }  // namespace disk_cache