metrics: Connect leak detector to allocator

base/allocator/allocator_extension.cc

Index: base/allocator/allocator_extension.cc
diff --git a/base/allocator/allocator_extension.cc b/base/allocator/allocator_extension.cc
index 17682f85d4950acd837f268056afa3ae49fc43c2..9a3d114f7290db53eb1b203a7d6309f8af7a9734 100644
--- a/base/allocator/allocator_extension.cc
+++ b/base/allocator/allocator_extension.cc
@@ -9,6 +9,7 @@
 #if defined(USE_TCMALLOC)
 #include "third_party/tcmalloc/chromium/src/gperftools/heap-profiler.h"
 #include "third_party/tcmalloc/chromium/src/gperftools/malloc_extension.h"
+#include "third_party/tcmalloc/chromium/src/gperftools/malloc_hook.h"
 #endif
 
 namespace base {
@@ -34,5 +35,26 @@ bool IsHeapProfilerRunning() {
   return false;
 }
 
+void SetHooks(AllocHookFunc alloc_hook, FreeHookFunc free_hook) {
+// TODO(sque): Use allocator shim layer instead.
+#if defined(USE_TCMALLOC)
+  // Make sure no hooks get overwritten.
+  auto prev_alloc_hook = MallocHook::SetNewHook(alloc_hook);
+  if (alloc_hook)
+    DCHECK(!prev_alloc_hook);
+
+  auto prev_free_hook = MallocHook::SetDeleteHook(free_hook);
+  if (free_hook)
+    DCHECK(!prev_free_hook);
+#endif
+}
+
+int GetCallStack(void** stack, int max_stack_size) {
+#if defined(USE_TCMALLOC)
+  return MallocHook::GetCallerStackTrace(stack, max_stack_size, 0);
+#endif
+  return 0;
+}
+
 }  // namespace allocator
 }  // namespace base