Serialize/Deserialize support in HistogramBase

chrome/common/metrics/metrics_log_base.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/common/metrics/metrics_log_base.h"
 
 #include "base/base64.h"
 #include "base/basictypes.h"
 #include "base/md5.h"
 #include "base/metrics/histogram_base.h"
@@ skipping 434 matching lines @@
   DCHECK(!locked_);
 
   int result = xmlTextWriterEndElement(xml_wrapper_->writer());
   DCHECK_GE(result, 0);
 }
 
 // TODO(JAR): A The following should really be part of the histogram class.
 // Internal state is being needlessly exposed, and it would be hard to reuse
 // this code. If we moved this into the Histogram class, then we could use
 // the same infrastructure for logging StatsCounters, RatesCounters, etc.
-void MetricsLogBase::RecordHistogramDelta(
-    const Histogram& histogram,
-    const HistogramSamples& snapshot) {
+void MetricsLogBase::RecordHistogramDelta(const std::string& histogram_name,
+                                          const HistogramSamples& snapshot) {
   DCHECK(!locked_);
   DCHECK_NE(0, snapshot.TotalCount());
 
   // We will ignore the MAX_INT/infinite value in the last element of range[].
 
   OPEN_ELEMENT_FOR_SCOPE("histogram");
 
   std::string base64_name_hash;
   uint64 numeric_name_hash;
-  CreateHashes(histogram.histogram_name(),
-               &base64_name_hash,
-               &numeric_name_hash);
+  CreateHashes(histogram_name, &base64_name_hash, &numeric_name_hash);
 
   // Write the XML version.
   WriteAttribute("name", base64_name_hash);
 
   WriteInt64Attribute("sum", snapshot.sum());
   // TODO(jar): Remove sumsquares when protobuffer accepts this as optional.
   WriteInt64Attribute("sumsquares", 0);
 
   for (scoped_ptr<SampleCountIterator> it = snapshot.Iterator();
        !it->Done();
@@ skipping 23 matching lines @@
     HistogramEventProto::Bucket* bucket = histogram_proto->add_bucket();
     bucket->set_min(min);
     bucket->set_max(max);
     bucket->set_count(count);
 
     size_t index;
     if (it->GetBucketIndex(&index))
       bucket->set_bucket_index(index);
   }
 }