Reland "Delete rtc::TaskQueue::Current in favor of webrtc::TaskQueueBase::Current"

This reverts commit 42d8c93ec351b68554825b58a3dc6525a7dc84da.

Reason for revert: Got Aliby for FEC test flakes

Original change's description:
> Revert "Delete rtc::TaskQueue::Current in favor of webrtc::TaskQueueBase::Current"
> 
> This reverts commit 304e9d2df347630d71fd4423f5971f30dac73e41.
> 
> Reason for revert: Breaks downstream projects.
> Seems to make VideoSendStreamTest.SupportsFlexfecSimulcastVp8 flaky.
> 
> Original change's description:
> > Delete rtc::TaskQueue::Current in favor of webrtc::TaskQueueBase::Current
> > 
> > Bug: webrtc:10191
> > Change-Id: I506cc50a90c73a6a4f6a3de36de0999cca72f5ba
> > Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/126230
> > Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
> > Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
> > Cr-Commit-Position: refs/heads/master@{#27035}
> 
> TBR=danilchap@webrtc.org,kwiberg@webrtc.org
> 
> Change-Id: If98324f88e4b3d18bf2fe33597dfb9711867c243
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: webrtc:10191
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/126484
> Reviewed-by: Yves Gerey <yvesg@webrtc.org>
> Commit-Queue: Yves Gerey <yvesg@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#27041}

TBR=danilchap@webrtc.org,kwiberg@webrtc.org,yvesg@webrtc.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: webrtc:10191
Change-Id: Id87a17ae415142b8e0b11ba03ae7bad84a473fb0
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/126720
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Yves Gerey <yvesg@webrtc.org>
Commit-Queue: Yves Gerey <yvesg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27056}
diff --git a/rtc_base/task_queue.h b/rtc_base/task_queue.h
index 1c0ae29..c42ce0f 100644
--- a/rtc_base/task_queue.h
+++ b/rtc_base/task_queue.h
@@ -57,8 +57,8 @@
 //      private:
 //       bool Run() override {
 //         ++count_;
-//         TaskQueue::Current()->PostDelayedTask(
-//             std::unique_ptr<QueuedTask>(this), 1000);
+//         TaskQueueBase::Current()->PostDelayedTask(
+//             absl::WrapUnique(this), 1000);
 //         // Ownership has been transferred to the next occurance,
 //         // so return false to prevent from being deleted now.
 //         return false;
@@ -66,8 +66,7 @@
 //       int count_ = 0;
 //     };
 //     ...
-//     queue_.PostDelayedTask(
-//         std::unique_ptr<QueuedTask>(new TimerTask()), 1000);
+//     queue_.PostDelayedTask(absl::make_unique<TimerTask>(), 1000);
 //
 // For more examples, see task_queue_unittests.cc.
 //
@@ -90,8 +89,6 @@
                      Priority priority = Priority::NORMAL);
   ~TaskQueue();
 
-  static TaskQueue* Current();
-
   // Used for DCHECKing the current queue.
   bool IsCurrent() const;