Add generic.total_physical_bytes property to MallocExtension

third_party/tcmalloc/chromium/src/gperftools/malloc_extension.h

 // Copyright (c) 2012, Google Inc.
 // All rights reserved.
 // 
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 // 
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
@@ skipping 141 matching lines @@
   //      Number of bytes currently allocated by application
   //      This property is not writable.
   //
   // "generic.heap_size"
   //      Number of bytes in the heap ==
   //            current_allocated_bytes +
   //            fragmentation +
   //            freed memory regions
   //      This property is not writable.
   //
+  //  "generic.total_physical_bytes"
+  //      Estimate of total bytes of the physical memory usage by the
+  //      allocator ==
+  //            current_allocated_bytes +
+  //            fragmentation +
+  //            metadata
+  //      This property is not writable.
+  //
   // tcmalloc
   // --------
   // "tcmalloc.max_total_thread_cache_bytes"
   //      Upper limit on total number of bytes stored across all
   //      per-thread caches.  Default: 16MB.
   //
   // "tcmalloc.current_total_thread_cache_bytes"
   //      Number of bytes used across all thread caches.
   //      This property is not writable.
   //
@@ skipping 226 matching lines @@
 
   // Perhaps add the following:
   // - stack trace if this range was sampled
   // - heap growth stack trace if applicable to this range
   // - age when allocated (for inuse) or freed (if not in use)
 };
 
 } // namespace base
 
 #endif  // BASE_MALLOC_EXTENSION_H_