Migrate off base::ThreadPool()-as-a-trait in...

Migrate off base::ThreadPool()-as-a-trait in /chrome/browser/media/webrtc/webrtc_event_log_manager.cc

This CL is a logical no-op.

It manually covers the use cases the script
(https://crbug.com/1026641#c22) didn't cover in
https://chromium-review.googlesource.com/c/chromium/src/+/2026350.

A few of the affected files were also migrated to
content::GetUIThreadTaskRunner() whenever surrounding code consistency
was at stake (but the bulk of that migration is staged to happen after
this one so this wasn't a priority in this batch).

Most files intentionally kept base/task/post_task.h as an include. It is
still required because of a cyclical dependency during the migration
preventing base/task/thread_pool.h from implicitly providing
base/task/task_traits.h to its users (callers that explicitly store
TaskTraits and include task_traits.h don't have this problem). The
post_task.h include will be cleaned up in a later phase.

This CL was uploaded by git cl split.

R=eladalon@chromium.org

Bug: 1026641
Change-Id: I1a06918db9cf2e701dfd03e9d6455eecdfdb0d9f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2079085
Commit-Queue: Gabriel Charette <gab@chromium.org>
Auto-Submit: Gabriel Charette <gab@chromium.org>
Reviewed-by: Elad Alon <eladalon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#745504}

chrome/browser/media/webrtc/webrtc_event_log_manager.cc

@@ -9,6 +9,7 @@
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/task/post_task.h"
+#include "base/task/thread_pool.h"
 #include "build/build_config.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/profiles/profile.h"
@@ -139,9 +140,8 @@ base::FilePath WebRtcEventLogManager::GetRemoteBoundWebRtcEventLogsDir(
 }
 
 WebRtcEventLogManager::WebRtcEventLogManager()
-    : task_runner_(base::CreateUpdateableSequencedTaskRunner(
-          {base::ThreadPool(), base::MayBlock(),
-           base::TaskPriority::BEST_EFFORT,
+    : task_runner_(base::ThreadPool::CreateUpdateableSequencedTaskRunner(
+          {base::MayBlock(), base::TaskPriority::BEST_EFFORT,
            base::ThreadPolicy::PREFER_BACKGROUND,
            base::TaskShutdownBehavior::SKIP_ON_SHUTDOWN})),
       num_user_blocking_tasks_(0),