Revert 41938 - Merged third_party/tcmalloc/vendor/src(googleperftools r87) in...

third_party/tcmalloc/chromium/src/base/low_level_alloc.h

Index: third_party/tcmalloc/chromium/src/base/low_level_alloc.h
===================================================================
--- third_party/tcmalloc/chromium/src/base/low_level_alloc.h	(revision 41940)
+++ third_party/tcmalloc/chromium/src/base/low_level_alloc.h	(working copy)
@@ -72,20 +72,14 @@
   // meta_data_arena; the DefaultArena() can be passed for meta_data_arena.
   // These values may be ored into flags:
   enum {
-    // Report calls to Alloc() and Free() via the MallocHook interface.
-    // Set in the DefaultArena.
-    kCallMallocHook = 0x0001,
-
-    // Make calls to Alloc(), Free() be async-signal-safe.  Not set in
-    // DefaultArena().
-    kAsyncSignalSafe = 0x0002,
-
-    // When used with DefaultArena(), the NewArena() and DeleteArena() calls
-    // obey the flags given explicitly in the NewArena() call, even if those
-    // flags differ from the settings in DefaultArena().  So the call
-    // NewArena(kAsyncSignalSafe, DefaultArena()) is itself async-signal-safe,
-    // as well as generatating an arena that provides async-signal-safe
-    // Alloc/Free.
+    // Calls to Alloc() and Free() will be reported
+    // via the MallocHook interface.
+    // The DefaultArena() has this flag on.
+    // NewArena(flags, DefaultArena()) w/o this bit in 'flags',
+    // on the other hand, will not cause any MallocHook
+    // calls even during the NewArena call itself
+    // (it will in fact use meta_data_arena different from DefaultArena()).
+    kCallMallocHook = 0x0001
   };
   static Arena *NewArena(int32 flags, Arena *meta_data_arena);