fix(DASH): Allow play all time fastSwitching tracks (#7180)

externs/shaka/abr_manager.js

@@ -60,12 +60,11 @@ shaka.extern.AbrManager = class {
 
   /**
    * Chooses one variant to switch to.  Called by the Player.
-   * @param {boolean=} preferFastSwitching If not provided meant "avoid fast
-   *                                       switching if possible".
+   *
    * @return {shaka.extern.Variant}
    * @exportDoc
    */
-  chooseVariant(preferFastSwitching) {}
+  chooseVariant() {}
 
   /**
    * Enables automatic Variant choices from the last ones passed to setVariants.

lib/abr/simple_abr_manager.js

@@ -167,12 +167,11 @@ shaka.abr.SimpleAbrManager = class {
 
 
   /**
-   * @param {boolean=} preferFastSwitching
    * @return {shaka.extern.Variant}
    * @override
    * @export
    */
-  chooseVariant(preferFastSwitching = false) {
+  chooseVariant() {
     let maxHeight = Infinity;
     let maxWidth = Infinity;
 
@@ -200,8 +199,7 @@ shaka.abr.SimpleAbrManager = class {
     }
 
     let variants = normalVariants;
-    if (preferFastSwitching &&
-        normalVariants.length != this.variants_.length) {
+    if (normalVariants.length != this.variants_.length) {
       variants = this.variants_.filter((variant) => {
         return variant && shaka.util.StreamUtils.isFastSwitching(variant);
       });

lib/media/preload_manager.js

@@ -634,8 +634,7 @@ shaka.media.PreloadManager = class extends shaka.util.FakeEventTarget {
       // Guess what the first variant will be, based on a SimpleAbrManager.
       this.abrManager_.configure(this.config_.abr);
       this.abrManager_.setVariants(Array.from(adaptationSet.values()));
-      const variant =
-          this.abrManager_.chooseVariant(/* preferFastSwitching= */ true);
+      const variant = this.abrManager_.chooseVariant();
       if (variant) {
         this.prefetchedVariant_ = variant;
         if (variant.video) {

lib/media/segment_prefetch.js

@@ -120,10 +120,6 @@ shaka.media.SegmentPrefetch = class {
         segmentPrefetchOperation.dispatchFetch(reference, this.stream_);
         this.segmentPrefetchMap_.set(reference, segmentPrefetchOperation);
       }
-      if (this.stream_.fastSwitching && reference.isPartial() &&
-          reference.isLastPartial()) {
-        break;
-      }
     }
     this.clearInitSegments_();
   }

lib/player.js

@@ -2458,7 +2458,7 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
     do {
       activeVariant = this.streamingEngine_.getCurrentVariant();
       if (!activeVariant && !initialVariant) {
-        initialVariant = this.chooseVariant_(/* initialSelection= */ true);
+        initialVariant = this.chooseVariant_();
         goog.asserts.assert(initialVariant, 'Must choose an initial variant!');
       }
 
@@ -3620,10 +3620,6 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
         this.onSegmentAppended_(
             reference.startTime, reference.endTime, stream.type,
             stream.codecs.includes(','));
-        if (this.abrManager_ && stream.fastSwitching &&
-            reference.isPartial() && reference.isLastPartial()) {
-          this.abrManager_.trySuggestStreams();
-        }
       },
       onInitSegmentAppended: (position, initSegment) => {
         const mediaQuality = initSegment.getMediaQuality();
@@ -6760,13 +6756,12 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
    *
    * On error, this dispatches an error event and returns null.
    *
-   * @param {boolean=} initialSelection
    * @return {?shaka.extern.Variant}
    * @private
    */
-  chooseVariant_(initialSelection = false) {
+  chooseVariant_() {
     if (this.updateAbrManagerVariants_()) {
-      return this.abrManager_.chooseVariant(initialSelection);
+      return this.abrManager_.chooseVariant();
     } else {
       return null;
     }