[tracing] Add native allocation tracing mode.

base/allocator/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/buildflag_header.gni")
 import("//build/config/allocator.gni")
 import("//build/config/compiler/compiler.gni")
 
 if (is_win) {
   import("//build/config/win/visual_studio_version.gni")
@@ skipping 280 matching lines @@
       configs -= [ "//build/config/compiler:default_optimization" ]
       configs += [ "//build/config/compiler:optimize_max" ]
     }
 
     deps += [ "//base/third_party/dynamic_annotations" ]
   }
 }  # use_allocator == "tcmalloc"
 
 buildflag_header("features") {
   header = "features.h"
-  flags = [ "USE_EXPERIMENTAL_ALLOCATOR_SHIM=$use_experimental_allocator_shim" ]
+  flags = [
+    "USE_EXPERIMENTAL_ALLOCATOR_SHIM=$use_experimental_allocator_shim",
+    "USE_EXPERIMENTAL_ALLOCATION_TRACING=$use_experimental_allocation_tracing",
+  ]
 }
 
 if (use_experimental_allocator_shim) {
   source_set("unified_allocator_shim") {
     # TODO(primiano): support other platforms, currently this works only on
     # Linux/CrOS. http://crbug.com/550886 .
     configs += [ "//base:base_implementation" ]  # for BASE_EXPORT
     visibility = [ "//base:base" ]
     sources = [
       "allocator_shim.cc",
       "allocator_shim.h",
       "allocator_shim_internals.h",
       "allocator_shim_override_cpp_symbols.h",
       "allocator_shim_override_libc_symbols.h",
     ]
     if (is_linux && use_allocator == "tcmalloc") {
       sources += [
         "allocator_shim_default_dispatch_to_tcmalloc.cc",
         "allocator_shim_override_glibc_weak_symbols.h",
       ]
       deps = [
         ":tcmalloc",
       ]
     } else if (is_linux && use_allocator == "none") {
       sources += [ "allocator_shim_default_dispatch_to_glibc.cc" ]
     }
   }
 }