Add peak memory usage metric

chrome/browser/metrics/chrome_metrics_service_client.h

 // 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.
 
 #ifndef CHROME_BROWSER_METRICS_CHROME_METRICS_SERVICE_CLIENT_H_
 #define CHROME_BROWSER_METRICS_CHROME_METRICS_SERVICE_CLIENT_H_
 
 #include <stdint.h>
 
 #include <deque>
@@ skipping 185 matching lines @@
 #endif
 
   // The DriveMetricsProvider instance that was registered with MetricsService.
   // Has the same lifetime as |metrics_service_|.
   metrics::DriveMetricsProvider* drive_metrics_provider_;
 
   // The MemoryGrowthTracker instance that tracks memory usage growth in
   // MemoryDetails.
   MemoryGrowthTracker memory_growth_tracker_;
 
+  // The PeakMemoryUsageTracker instance that tracks peak memory usage in
+  // MemoryDetails.
+  PeakMemoryUsageTracker peak_memory_usage_tracker_;
+
   // Callback to determine whether or not a cellular network is currently being
   // used.
   base::Callback<void(bool*)> cellular_callback_;
 
   // Time of this object's creation.
   const base::TimeTicks start_time_;
 
   // Subscription for receiving callbacks that a URL was opened from the
   // omnibox.
   std::unique_ptr<base::CallbackList<void(OmniboxLog*)>::Subscription>
       omnibox_url_opened_subscription_;
 
   // Whether this client has already uploaded profiler data during this session.
   // Profiler data is uploaded at most once per session.
   bool has_uploaded_profiler_data_;
 
   base::WeakPtrFactory<ChromeMetricsServiceClient> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeMetricsServiceClient);
 };
 
 #endif  // CHROME_BROWSER_METRICS_CHROME_METRICS_SERVICE_CLIENT_H_