Removed MallocHookScope and replaced it with MallocLocker, which behaves like MutexLocker but also …

runtime/vm/os_thread.h

Index: runtime/vm/os_thread.h
diff --git a/runtime/vm/os_thread.h b/runtime/vm/os_thread.h
index 41e77180ed74cf2dd256c4eede7dd3882b2faaab..a3693af4308fc901af326e7c946fc992f7f3add1 100644
--- a/runtime/vm/os_thread.h
+++ b/runtime/vm/os_thread.h
@@ -291,6 +291,7 @@ class Mutex {
   ThreadId owner_;
 #endif  // defined(DEBUG)
 
+  friend class MallocLocker;

[siva, 2017/02/22 23:53:04]

Why is this needed here, doesn't seem right.

[bkonyi, 2017/02/23 00:28:46]

This is needed for MallocLocker to be able to access the various methods needed
to take/release a Mutex as they are all private. Otherwise, we can't perform any
operations with the Mutex within MallocLocker.

   friend class MutexLocker;
   friend class SafepointMutexLocker;
   friend class OSThreadIterator;