Add peak memory usage metric

chrome/browser/metrics/chrome_metrics_service_client.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 "chrome/browser/metrics/chrome_metrics_service_client.h"
 
 #include <stddef.h>
 
 #include <utility>
 #include <vector>
@@ skipping 724 matching lines @@
   // finished, it will call OnMemoryDetailCollectionDone. That will in turn
   // call HistogramSynchronization to collect histograms from all renderers and
   // then call OnHistogramSynchronizationDone to continue processing.
   DCHECK(!waiting_for_collect_final_metrics_step_);
   waiting_for_collect_final_metrics_step_ = true;
 
   base::Closure callback =
       base::Bind(&ChromeMetricsServiceClient::OnMemoryDetailCollectionDone,
                  weak_ptr_factory_.GetWeakPtr());
 
-  scoped_refptr<MetricsMemoryDetails> details(
-      new MetricsMemoryDetails(callback, &memory_growth_tracker_));
+  scoped_refptr<MetricsMemoryDetails> details(new MetricsMemoryDetails(
+      callback, &memory_growth_tracker_, &peak_memory_usage_tracker_));
   details->StartFetch();
 }
 
 void ChromeMetricsServiceClient::MergeHistogramDeltas() {
   DCHECK(GetMetricsService());
   GetMetricsService()->MergeHistogramDeltas();
 }
 
 void ChromeMetricsServiceClient::OnMemoryDetailCollectionDone() {
   DCHECK(thread_checker_.CalledOnValidThread());
@@ skipping 127 matching lines @@
   }
 }
 
 void ChromeMetricsServiceClient::OnURLOpenedFromOmnibox(OmniboxLog* log) {
   metrics_service_->OnApplicationNotIdle();
 }
 
 bool ChromeMetricsServiceClient::IsUMACellularUploadLogicEnabled() {
   return metrics::IsCellularLogicEnabled();
 }