Add experimental private memory footprint metrics.

chrome/browser/memory_details.h

 // 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.
 
 #ifndef CHROME_BROWSER_MEMORY_DETAILS_H_
 #define CHROME_BROWSER_MEMORY_DETAILS_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 54 matching lines @@
   int num_open_fds;
   // Maximum number of file descriptors that can be opened in this process.
   int open_fds_soft_limit;
   // If this is a renderer process, what type it is.
   RendererProcessType renderer_type;
   // A collection of titles used, i.e. for a tab it'll show all the page titles.
   std::vector<base::string16> titles;
   // The physical footprint is a macOS concept that tracks anonymous,
   // non-discardable memory.
   size_t phys_footprint;
+  // TODO(erikchen): Remove this temporary estimate for private memory once the
+  // memory infra service emits the same metric. https://crbug.com/720541.
+  size_t private_memory_footprint;
 };
 
 typedef std::vector<ProcessMemoryInformation> ProcessMemoryInformationList;
 
 // Browser Process Information.
 struct ProcessData {
   ProcessData();
   ProcessData(const ProcessData& rhs);
   ~ProcessData();
   ProcessData& operator=(const ProcessData& rhs);
@@ skipping 88 matching lines @@
   std::vector<ProcessData> process_data_;
 
 #if defined(OS_CHROMEOS)
   base::SwapInfo swap_info_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(MemoryDetails);
 };
 
 #endif  // CHROME_BROWSER_MEMORY_DETAILS_H_