[Tracing] Add lookup support to AllocationRegister

base/trace_event/heap_profiler_allocation_register.h

Index: base/trace_event/heap_profiler_allocation_register.h
diff --git a/base/trace_event/heap_profiler_allocation_register.h b/base/trace_event/heap_profiler_allocation_register.h
index b8afa6b8ed65f76b9dee4e13beeeae57aac93e1f..804be898e4d1d4957d7f394404760fd0c8f96ca5 100644
--- a/base/trace_event/heap_profiler_allocation_register.h
+++ b/base/trace_event/heap_profiler_allocation_register.h
@@ -34,7 +34,7 @@ class BASE_EXPORT AllocationRegister {
   // The data stored in the hash table;
   // contains the details about an allocation.
   struct Allocation {
-    void* address;
+    void* const address;
     size_t size;
     AllocationContext context;
   };
@@ -75,6 +75,11 @@ class BASE_EXPORT AllocationRegister {
   // with a null pointer.
   void Remove(void* address);
 
+  // Returns a pointer to the allocation at the address, or null if there is no
+  // allocation at that address. This can be used to change the allocation
+  // context after insertion, for example to change the type name.
+  Allocation* Get(void* address);
+
   ConstIterator begin() const;
   ConstIterator end() const;