Report expected task queueing time via UMA

components/scheduler/scheduler.gypi

 # 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.
 
 {
   'variables': {
     'scheduler_common_sources': [
       # Sources list duplicated in GN build.
       'common/scheduler_switches.cc',
       'common/scheduler_switches.h',
     ],
     'scheduler_sources': [
       # Sources list duplicated in GN build.
       'base/cancelable_closure_holder.cc',
       'base/cancelable_closure_holder.h',
       'base/lazy_now.cc',
       'base/lazy_now.h',
+      'base/queueing_time_estimator.cc',
+      'base/queueing_time_estimator.h',
       'base/real_time_domain.cc',
       'base/real_time_domain.h',
       'base/task_queue.h',
       'base/task_queue_impl.cc',
       'base/task_queue_impl.h',
       'base/task_queue_manager.cc',
       'base/task_queue_manager.h',
       'base/task_queue_manager_delegate.h',
       'base/task_queue_selector.cc',
       'base/task_queue_selector.h',
+      'base/task_time_tracker.h',
       'base/time_domain.cc',
       'base/time_domain.h',
       'base/work_queue.cc',
       'base/work_queue.h',
       'base/work_queue_sets.cc',
       'base/work_queue_sets.h',
       'base/pollable_thread_safe_flag.cc',
       'base/pollable_thread_safe_flag.h',
       'base/virtual_time_domain.cc',
       'base/virtual_time_domain.h',
@@ skipping 57 matching lines @@
     ],
     'scheduler_test_support_sources': [
       # Sources list duplicated in GN build.
       'test/lazy_scheduler_message_loop_delegate_for_tests.cc',
       'test/lazy_scheduler_message_loop_delegate_for_tests.h',
       'test/renderer_scheduler_test_support.h',
       'test/renderer_scheduler_test_support.cc',
     ],
   },
 }