Update from https://crrev.com/333737

base/trace_event/process_memory_maps.h

 // Copyright 2015 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 BASE_TRACE_EVENT_PROCESS_MEMORY_MAPS_H_
 #define BASE_TRACE_EVENT_PROCESS_MEMORY_MAPS_H_
 
 #include <string>
 #include <vector>
 
 #include "base/base_export.h"
 #include "base/basictypes.h"
 
 namespace base {
 namespace trace_event {
 
 class TracedValue;
 
 // Data model for process-wide memory stats.
 class BASE_EXPORT ProcessMemoryMaps {
  public:
-  struct VMRegion {
+  struct BASE_EXPORT VMRegion {
     static const uint32 kProtectionFlagsRead;
     static const uint32 kProtectionFlagsWrite;
     static const uint32 kProtectionFlagsExec;
 
+    VMRegion();
+
     uint64 start_address;
     uint64 size_in_bytes;
     uint32 protection_flags;
     std::string mapped_file;
 
-    // private_resident + shared_resident = resident set size.
-    uint64 byte_stats_private_resident;
-    uint64 byte_stats_shared_resident;
+    // private_dirty_resident + private_clean_resident + shared_dirty_resident +
+    // shared_clean_resident = resident set size.
+    uint64 byte_stats_private_dirty_resident;
+    uint64 byte_stats_private_clean_resident;
+    uint64 byte_stats_shared_dirty_resident;
+    uint64 byte_stats_shared_clean_resident;
+
+    uint64 byte_stats_swapped;
 
     // For multiprocess accounting.
     uint64 byte_stats_proportional_resident;
   };
 
   ProcessMemoryMaps();
   ~ProcessMemoryMaps();
 
   void AddVMRegion(const VMRegion& region) { vm_regions_.push_back(region); }
   const std::vector<VMRegion>& vm_regions() const { return vm_regions_; }
 
   // Called at trace generation time to populate the TracedValue.
   void AsValueInto(TracedValue* value) const;
 
+  // Clears up all the VMRegion(s) stored.
+  void Clear();
+
  private:
   std::vector<VMRegion> vm_regions_;
 
   DISALLOW_COPY_AND_ASSIGN(ProcessMemoryMaps);
 };
 
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_PROCESS_MEMORY_MAPS_H_