Add EnabledStateObserver to BackgroundTracingManager

content/browser/BUILD.gn

 # Copyright 2014 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/config/features.gni")
 import("//build/config/ui.gni")
 import("//gpu/vulkan/features.gni")
 import("//media/media_options.gni")
 import("//ppapi/features/features.gni")
 import("//printing/features/features.gni")
@@ skipping 1373 matching lines @@
     "streams/stream_register_observer.h",
     "streams/stream_registry.cc",
     "streams/stream_registry.h",
     "streams/stream_url_request_job.cc",
     "streams/stream_url_request_job.h",
     "streams/stream_write_observer.h",
     "theme_helper_mac.h",
     "theme_helper_mac.mm",
     "tracing/arc_tracing_agent.cc",
     "tracing/arc_tracing_agent.h",
+    "tracing/background_memory_tracing_observer.cc",
+    "tracing/background_memory_tracing_observer.h",
     "tracing/background_tracing_config_impl.cc",
     "tracing/background_tracing_config_impl.h",
     "tracing/background_tracing_manager_impl.cc",
     "tracing/background_tracing_manager_impl.h",
     "tracing/background_tracing_rule.cc",
     "tracing/background_tracing_rule.h",
     "tracing/etw_tracing_agent_win.cc",
     "tracing/etw_tracing_agent_win.h",
     "tracing/file_tracing_provider_impl.cc",
     "tracing/file_tracing_provider_impl.h",
@@ skipping 650 matching lines @@
   if (!is_component_build) {
     public_deps = [
       ":browser",
     ]
   } else {
     public_deps = [
       "//third_party/leveldatabase",
     ]
   }
 }