Updated MallocHooks to collect stack traces when memory is allocated.

runtime/vm/malloc_hooks.h

Index: runtime/vm/malloc_hooks.h
diff --git a/runtime/vm/malloc_hooks.h b/runtime/vm/malloc_hooks.h
index 852c7992ec80c696b37a8d35ea0a0afa256fe3b4..4c2419c74f0e30b88105087939bbf6372c7a441d 100644
--- a/runtime/vm/malloc_hooks.h
+++ b/runtime/vm/malloc_hooks.h
@@ -7,21 +7,23 @@
 
 #include "vm/globals.h"
 
+#include "vm/allocation.h"
+
 namespace dart {
 
-class MallocHooks {
+class Sample;
+
+class MallocHooks : public AllStatic {
  public:
   static void InitOnce();
   static void TearDown();
+  static bool stack_trace_collection_enabled();
   static void ResetStats();
   static bool Initialized();
+  static Sample* GetSample(const void* ptr);
 
   static intptr_t allocation_count();
   static intptr_t heap_allocated_memory_in_bytes();
-
- private:
-  DISALLOW_ALLOCATION();
-  DISALLOW_IMPLICIT_CONSTRUCTORS(MallocHooks);
 };
 
 }  // namespace dart