Implement a ScopedThreadHeapUsage class to allow profiling per-thread heap usage.

base/trace_event/malloc_dump_provider.cc

Index: base/trace_event/malloc_dump_provider.cc
diff --git a/base/trace_event/malloc_dump_provider.cc b/base/trace_event/malloc_dump_provider.cc
index d7732aba664ebf38532d247c562c1df98ebe62e2..0258386deb3e527d93492a95391e425e6775430b 100644
--- a/base/trace_event/malloc_dump_provider.cc
+++ b/base/trace_event/malloc_dump_provider.cc
@@ -77,13 +77,21 @@ void HookFree(const AllocatorDispatch* self, void* address) {
   next->free_function(next, address);
 }
 
+size_t HookGetSizeEstimate(const AllocatorDispatch* self, void* address) {
+  const AllocatorDispatch* const next = self->next;
+  if (!next->get_size_estimate_function)

[Primiano Tucci (use gerrit), 2016/09/07 17:53:38]

not sure we need this level of protection here right? it should never happen
that the ptr is null. if not supported this should have a return 0
implementation, but the elements of the chain shouldn't be bothered to make this
check

[Sigurður Ásgeirsson, 2016/09/07 18:35:35]

Done.

+    return 0;
+  return next->get_size_estimate_function(next, address);
+}
+
 AllocatorDispatch g_allocator_hooks = {
-    &HookAlloc,         /* alloc_function */
-    &HookZeroInitAlloc, /* alloc_zero_initialized_function */
-    &HookllocAligned,   /* alloc_aligned_function */
-    &HookRealloc,       /* realloc_function */
-    &HookFree,          /* free_function */
-    nullptr,            /* next */
+    &HookAlloc,           /* alloc_function */
+    &HookZeroInitAlloc,   /* alloc_zero_initialized_function */
+    &HookllocAligned,     /* alloc_aligned_function */
+    &HookRealloc,         /* realloc_function */
+    &HookFree,            /* free_function */
+    &HookGetSizeEstimate, /* get_size_estimate_function */
+    nullptr,              /* next */
 };
 #endif  // BUILDFLAG(USE_EXPERIMENTAL_ALLOCATOR_SHIM)