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

base/allocator/allocator_shim_default_dispatch_to_linker_wrapped_symbols.cc

Index: base/allocator/allocator_shim_default_dispatch_to_linker_wrapped_symbols.cc
diff --git a/base/allocator/allocator_shim_default_dispatch_to_linker_wrapped_symbols.cc b/base/allocator/allocator_shim_default_dispatch_to_linker_wrapped_symbols.cc
index 7955cb7877001e7c6a7a73ea4505f5aa24c24f6b..4c595f91ab3988323027fd40a6179b351055e3a0 100644
--- a/base/allocator/allocator_shim_default_dispatch_to_linker_wrapped_symbols.cc
+++ b/base/allocator/allocator_shim_default_dispatch_to_linker_wrapped_symbols.cc
@@ -45,13 +45,19 @@ void RealFree(const AllocatorDispatch*, void* address) {
   __real_free(address);
 }
 
+size_t RealSizeEstimate(const AllocatorDispatch*, void*) {
+  // TODO(siggi): I can't figure out how to direct this to malloc_usable_size.
+  return 0;

[Primiano Tucci (use gerrit), 2016/08/24 15:28:46]

I can take care of this later.
The trick here is to add malloc_usable_size to the wrapped symbols in
base/allocator/BUILD.gn, which will give a __real_malloc_usable_size here (but
requires the shim to expose a symbol to route the __wrap_malloc_usable_size
into).
Fine to leave it with a TODO for the moment.

[Sigurður Ásgeirsson, 2016/09/01 15:18:18]

Thanks, I've left you a TODO.

+}
+
 }  // namespace
 
 const AllocatorDispatch AllocatorDispatch::default_dispatch = {
-    &RealMalloc,   /* alloc_function */
-    &RealCalloc,   /* alloc_zero_initialized_function */
-    &RealMemalign, /* alloc_aligned_function */
-    &RealRealloc,  /* realloc_function */
-    &RealFree,     /* free_function */
-    nullptr,       /* next */
+    &RealMalloc,       /* alloc_function */
+    &RealCalloc,       /* alloc_zero_initialized_function */
+    &RealMemalign,     /* alloc_aligned_function */
+    &RealRealloc,      /* realloc_function */
+    &RealFree,         /* free_function */
+    &RealSizeEstimate, /* get_size_estimate_function */
+    nullptr,           /* next */
 };