Update from https://crrev.com/333737

base/trace_event/process_memory_maps.h

Index: base/trace_event/process_memory_maps.h
diff --git a/base/trace_event/process_memory_maps.h b/base/trace_event/process_memory_maps.h
index dc1892fd6221852efebc870aba50f72c1da62f18..b06a85037a57a2a917b5b1110bcda70202d45381 100644
--- a/base/trace_event/process_memory_maps.h
+++ b/base/trace_event/process_memory_maps.h
@@ -19,19 +19,26 @@ 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;
@@ -46,6 +53,9 @@ class BASE_EXPORT ProcessMemoryMaps {
   // 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_;