Consolidate serialization code in base::HistogramDeltasSerializer.

content/browser/histogram_synchronizer.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 "content/browser/histogram_synchronizer.h"
 
 #include "base/bind.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
+#include "base/metrics/histogram_delta_serialization.h"
 #include "base/pickle.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_restrictions.h"
 #include "content/browser/histogram_controller.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/histogram_fetcher.h"
 #include "content/public/common/content_constants.h"
 
 using base::Time;
 using base::TimeDelta;
@@ skipping 240 matching lines @@
   request->AddProcessesPending(pending_processes);
   request->SetReceivedProcessGroupCount(end);
   request->DeleteIfAllDone();
 }
 
 void HistogramSynchronizer::OnHistogramDataCollected(
     int sequence_number,
     const std::vector<std::string>& pickled_histograms) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
+  base::HistogramDeltaSerialization::DeserializeAndAddSamples(
+      pickled_histograms);
+
   RequestContext* request = RequestContext::GetRequestContext(sequence_number);
-
-  for (std::vector<std::string>::const_iterator it = pickled_histograms.begin();
-       it < pickled_histograms.end();
-       ++it) {
-    Pickle pickle(it->data(), it->size());
-    PickleIterator iter(pickle);
-    base::DeserializeHistogramAndAddSamples(&iter);
-  }
-
   if (!request)
     return;
 
   // Delete request if we have heard back from all child processes.
   request->DecrementProcessesPending();
   request->DeleteIfAllDone();
 }
 
 void HistogramSynchronizer::SetCallbackTaskAndThread(
     base::MessageLoop* callback_thread,
@@ skipping 48 matching lines @@
         kHistogramSynchronizerReservedSequenceNumber + 1;
   }
   DCHECK_NE(last_used_sequence_number_,
             kHistogramSynchronizerReservedSequenceNumber);
   if (requester == ASYNC_HISTOGRAMS)
     async_sequence_number_ = last_used_sequence_number_;
   return last_used_sequence_number_;
 }
 
 }  // namespace content