Remove task_queue dependency for QualityScaler

This allows for the possiblity to move the QualityScaler
out of the VideoStreamEncoder in the future.


Bug: webrtc:11222
Change-Id: I1d563cf08791e27ff5065ce90bcb150a7974d868
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/167534
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Reviewed-by: Erik Språng <sprang@webrtc.org>
Commit-Queue: Evan Shrubsole <eshr@google.com>
Cr-Commit-Position: refs/heads/master@{#30406}

modules/video_coding/utility/quality_scaler.h

@@ -53,8 +53,7 @@ class QualityScaler {
   // Construct a QualityScaler with given |thresholds| and |observer|.
   // This starts the quality scaler periodically checking what the average QP
   // has been recently.
-  QualityScaler(rtc::TaskQueue* task_queue,
-                AdaptationObserverInterface* observer,
+  QualityScaler(AdaptationObserverInterface* observer,
                 VideoEncoder::QpThresholds thresholds);
   virtual ~QualityScaler();
   // Should be called each time a frame is dropped at encoding.
@@ -68,8 +67,7 @@ class QualityScaler {
 
   // The following members declared protected for testing purposes.
  protected:
-  QualityScaler(rtc::TaskQueue* task_queue,
-                AdaptationObserverInterface* observer,
+  QualityScaler(AdaptationObserverInterface* observer,
                 VideoEncoder::QpThresholds thresholds,
                 int64_t sampling_period_ms);