Fix: Fix clearing buffer when requested for already-selected variant (#3477)

Close: #3450

Author: Álvaro Velad Galván

lib/media/streaming_engine.js

@@ -317,8 +317,10 @@ shaka.media.StreamingEngine = class {
    * @param {shaka.extern.Variant} variant
    * @param {boolean=} clearBuffer
    * @param {number=} safeMargin
+   * @param {boolean=} force
+   *   If true, reload the variant even if it did not change.
    */
-  switchVariant(variant, clearBuffer = false, safeMargin = 0) {
+  switchVariant(variant, clearBuffer = false, safeMargin = 0, force = false) {
     this.currentVariant_ = variant;
 
     if (!this.startupComplete_) {
@@ -329,12 +331,12 @@ shaka.media.StreamingEngine = class {
     if (variant.video) {
       this.switchInternal_(
           variant.video, /* clearBuffer= */ clearBuffer,
-          /* safeMargin= */ safeMargin, /* force= */ false);
+          /* safeMargin= */ safeMargin, /* force= */ force);
     }
     if (variant.audio) {
       this.switchInternal_(
           variant.audio, /* clearBuffer= */ clearBuffer,
-          /* safeMargin= */ safeMargin, /* force= */ false);
+          /* safeMargin= */ safeMargin, /* force= */ force);
     }
   }
 

lib/player.js

@@ -4968,6 +4968,11 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
     const currentVariant = this.streamingEngine_.getCurrentVariant();
     if (variant == currentVariant) {
       shaka.log.debug('Variant already selected.');
+      // If you want to clear the buffer, we force to reselect the same variant
+      if (clearBuffer) {
+        this.streamingEngine_.switchVariant(variant, clearBuffer, safeMargin,
+            /* force= */ true);
+      }
       return;
     }