[ThreadPool] Rename remaining types

 * SchedulerWorker => WorkerThread
 * SchedulerWorkerPool => ThreadGroup
 * SchedulerWorkerPoolParams => ThreadGroupParams
 * PlatformNativeWorkerPool => ThreadGroupNative
 * Scheduler*TaskRunner* => Pooled*TaskRunner*
  (including SchedulerSingleThreadTaskRunnerManager)

 => Used tools/git/move_source_file.py for move.
 => Used mass-search-and-replace with above names
 => Also mass-renamed variable in snake_case matching above names.
 => Manually searched for "WorkerPool" and fixed remaining usage.

 * SchedulerFooTest/ThreadPoolFooTest => FooTest
   (for types that are standalone; kept ThreadPool* prefix for some)

 * Also renamed remaining "Scheduler" nomenclature in
   components/thread_pool_util (means variations names are changing)

[email protected]

TBR=eroman (net/ side-effects)
TBR=ganesh (chrome/updater side-effects)

Bug: 951388
Change-Id: Iff84e4d37ed0942c4ff8c6fb4029478e8ce1529b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1590408
Commit-Queue: Gabriel Charette <[email protected]>
Reviewed-by: François Doray <[email protected]>
Reviewed-by: Lei Zhang <[email protected]>
Reviewed-by: Rohit Rao <[email protected]>
Reviewed-by: David Bienvenu <[email protected]>
Reviewed-by: Avi Drissman <[email protected]>
Cr-Commit-Position: refs/heads/master@{#655594}
diff --git a/base/task/task_features.h b/base/task/task_features.h
index 21d8719..cc24bd69 100644
--- a/base/task/task_features.h
+++ b/base/task/task_features.h
@@ -16,7 +16,7 @@
 extern const BASE_EXPORT Feature kAllTasksUserBlocking;
 extern const BASE_EXPORT Feature kMergeBlockingNonBlockingPools;
 
-// Under this feature, unused threads in SchedulerWorkerPool are only detached
+// Under this feature, unused threads in ThreadGroup are only detached
 // if the total number of threads in the pool is above the initial capacity.
 extern const BASE_EXPORT Feature kNoDetachBelowInitialCapacity;
 
@@ -25,7 +25,7 @@
 extern const BASE_EXPORT Feature kMayBlockWithoutDelay;
 
 #if defined(OS_WIN) || defined(OS_MACOSX)
-// Under this feature, ThreadPool will use a SchedulerWorkerPool backed by a
+// Under this feature, ThreadPool will use a ThreadGroup backed by a
 // native thread pool implementation. The Windows Thread Pool API and
 // libdispatch are used on Windows and macOS/iOS respectively.
 extern const BASE_EXPORT Feature kUseNativeThreadPool;