Remove allocator_extension_thunks since this layer is not required

base/trace_event/BUILD.gn

 # Copyright 2015 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.
 
 source_set("trace_event") {
   sources = [
     "common/trace_event_common.h",
     "heap_profiler_allocation_context.cc",
     "heap_profiler_allocation_context.h",
     "heap_profiler_allocation_context_tracker.cc",
@@ skipping 72 matching lines @@
       "process_memory_totals_dump_provider.cc",
       "trace_event_system_stats_monitor.cc",
     ]
   }
 
   if (is_linux || is_android || is_mac) {
     sources += [
       "malloc_dump_provider.cc",
       "malloc_dump_provider.h",
     ]
-    deps += [ "//base/allocator:extension_thunks" ]
   }
 
   if (is_linux || is_android) {
     sources += [ "process_memory_maps_dump_provider.cc" ]
   }
   if (is_win) {
     deps += [ "//base/trace_event/etw_manifest:chrome_events_win" ]
   }
 
   allow_circular_includes_from = [
@@ skipping 34 matching lines @@
   if (is_android) {
     sources += [ "trace_event_android_unittest.cc" ]
   }
 
   deps = [
     "//base/test:test_support",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }