Merge tcmalloc r111 (perftools v. 1.8) with the chromium/ branch.

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

 /* Copyright (c) 2006, 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 215 matching lines @@
         sigfillset(&all);
         this->mask_valid_ =
             (pthread_sigmask(SIG_BLOCK, &all, &this->mask_) == 0);
 #else
         RAW_CHECK(false, "We do not yet support async-signal-safe arena.");
 #endif
       }
       this->arena_->mu.Lock();
     }
     ~ArenaLock() { RAW_CHECK(this->left_, "haven't left Arena region"); }
-    void Leave() UNLOCK_FUNCTION() {
+    void Leave() /*UNLOCK_FUNCTION()*/ {
       this->arena_->mu.Unlock();
 #if 0
       if (this->mask_valid_) {
         pthread_sigmask(SIG_SETMASK, &this->mask_, 0);
       }
 #endif
       this->left_ = true;
     }
    private:
     bool left_;       // whether left region
@@ skipping 266 matching lines @@
     // this call must be directly in the user-called allocator function
     // for MallocHook::GetCallerStackTrace to work properly
     MallocHook::InvokeNewHook(result, request);
   }
   return result;
 }
 
 LowLevelAlloc::Arena *LowLevelAlloc::DefaultArena() {
   return &default_arena;
 }