metrics: Connect leak detector to allocator

base/allocator/allocator_extension.h

Index: base/allocator/allocator_extension.h
diff --git a/base/allocator/allocator_extension.h b/base/allocator/allocator_extension.h
index 64bfd1cc4acaa3fe2a8fc1e8f80ab1fe674f3856..9f2775a427fa73de1ca221eb7d646209b048b271 100644
--- a/base/allocator/allocator_extension.h
+++ b/base/allocator/allocator_extension.h
@@ -13,6 +13,10 @@
 namespace base {
 namespace allocator {
 
+// Callback types for alloc and free.
+using AllocHookFunc = void (*)(const void*, size_t);
+using FreeHookFunc = void (*)(const void*);
+
 // Request that the allocator release any free memory it knows about to the
 // system.
 BASE_EXPORT void ReleaseFreeMemory();
@@ -25,6 +29,22 @@ BASE_EXPORT bool GetNumericProperty(const char* name, size_t* value);
 
 BASE_EXPORT bool IsHeapProfilerRunning();
 
+// Register callbacks for alloc and free. Can only store one callback at a time
+// for each of alloc and free.
+BASE_EXPORT void SetHooks(AllocHookFunc alloc_hook, FreeHookFunc free_hook);
+
+// Attempts to unwind the call stack from the current location where this
+// function is being called from. Must be called from a hook function registered
+// by calling SetSingle{Alloc,Free}Hook, directly or indirectly.
+//
+// Arguments:
+//   stack:          pointer to a pre-allocated array of void*'s.
+//   max_stack_size: indicates the size of the array in |stack|.
+//
+// Returns the number of call stack frames stored in |stack|, or 0 if no call
+// stack information is available.
+BASE_EXPORT int GetCallStack(void** stack, int max_stack_size);
+
 }  // namespace allocator
 }  // namespace base