memory-infra: Start disentangling tracing from memory-infra

base/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.
 
 # HOW TO WRITE CONDITIONALS IN THIS FILE
 # ======================================
 #
 # In many other places, one would write a conditional that expresses all the
 # cases when a source file is used or unused, and then either add or subtract
 # it from the sources list in that case
@@ skipping 963 matching lines @@
     "trace_event/memory_dump_request_args.cc",
     "trace_event/memory_dump_request_args.h",
     "trace_event/memory_dump_scheduler.cc",
     "trace_event/memory_dump_scheduler.h",
     "trace_event/memory_dump_session_state.cc",
     "trace_event/memory_dump_session_state.h",
     "trace_event/memory_infra_background_whitelist.cc",
     "trace_event/memory_infra_background_whitelist.h",
     "trace_event/memory_peak_detector.cc",
     "trace_event/memory_peak_detector.h",
+    "trace_event/memory_tracing_observer.cc",
+    "trace_event/memory_tracing_observer.h",
     "trace_event/memory_usage_estimator.cc",
     "trace_event/memory_usage_estimator.h",
     "trace_event/process_memory_dump.cc",
     "trace_event/process_memory_dump.h",
     "trace_event/process_memory_maps.cc",
     "trace_event/process_memory_maps.h",
     "trace_event/process_memory_totals.cc",
     "trace_event/process_memory_totals.h",
     "trace_event/trace_buffer.cc",
     "trace_event/trace_buffer.h",
@@ skipping 1699 matching lines @@
 }
 
 fuzzer_test("base_json_correctness_fuzzer") {
   sources = [
     "json/correctness_fuzzer.cc",
   ]
   deps = [
     ":base",
   ]
 }