Update the tcmalloc vendor branch to r144 (gperftools 2.0).

third_party/tcmalloc/vendor/src/memory_region_map.h

Index: third_party/tcmalloc/vendor/src/memory_region_map.h
diff --git a/third_party/tcmalloc/vendor/src/memory_region_map.h b/third_party/tcmalloc/vendor/src/memory_region_map.h
index 739514c22c61d0299402c4d69c62cffd6cc98985..988ea707375aed124136fe0bb7db105dbb2952a7 100644
--- a/third_party/tcmalloc/vendor/src/memory_region_map.h
+++ b/third_party/tcmalloc/vendor/src/memory_region_map.h
@@ -252,6 +252,10 @@ class MemoryRegionMap {
   static RegionIterator BeginRegionLocked();
   static RegionIterator EndRegionLocked();
 
+  // Return the accumulated sizes of mapped and unmapped regions.
+  static int64 MapSize() { return map_size_; }
+  static int64 UnmapSize() { return unmap_size_; }
+
   // Effectively private type from our .cc =================================
   // public to let us declare global objects:
   union RegionSetRep;
@@ -286,6 +290,11 @@ class MemoryRegionMap {
   // The thread id of the thread that's inside the recursive lock.
   static pthread_t lock_owner_tid_;
 
+  // Total size of all mapped pages so far
+  static int64 map_size_;
+  // Total size of all unmapped pages so far
+  static int64 unmap_size_;
+
   // helpers ==================================================================
 
   // Helper for FindRegion and FindAndMarkStackRegion: