refactor(HLS): Refactor URLs management in HLS (#5864)

It also improves the detection of duplicate playlists, and improves
redirect management, leaving the original URL available in case it is
needed.

lib/hls/hls_classes.js

@@ -19,19 +19,11 @@ goog.require('shaka.util.Error');
  */
 shaka.hls.Playlist = class {
   /**
-   * @param {string} absoluteUri An absolute, final URI after redirects.
    * @param {!shaka.hls.PlaylistType} type
    * @param {!Array.<shaka.hls.Tag>} tags
    * @param {!Array.<shaka.hls.Segment>=} segments
    */
-  constructor(absoluteUri, type, tags, segments) {
-    /**
-     * An absolute, final URI after redirects.
-     *
-     * @const {string}
-     */
-    this.absoluteUri = absoluteUri;
-
+  constructor(type, tags, segments) {
     /** @const {shaka.hls.PlaylistType} */
     this.type = type;
 
@@ -86,10 +78,11 @@ shaka.hls.Tag = class {
    * As in some cases (like in tests) the tag never existed in string form, it
    * is far easier to recreate the tag from the parsed form.
    *
+   * @param {?Set.<string>=} attributesToSkip
    * @return {string}
    * @override
    */
-  toString() {
+  toString(attributesToSkip) {
     /**
      * @param {shaka.hls.Attribute} attr
      * @return {string}
@@ -106,7 +99,12 @@ shaka.hls.Tag = class {
     //  4) <NAME>:<VALUE>,<ATTRIBUTE_LIST>
 
     let tagStr = '#' + this.name;
-    const appendages = this.attributes ? this.attributes.map(attrToStr) : [];
+    const appendages = this.attributes ? this.attributes.filter((attr) => {
+      if (!attributesToSkip) {
+        return true;
+      }
+      return !attributesToSkip.has(attr.name);
+    }).map(attrToStr) : [];
 
     if (this.value) {
       appendages.unshift(this.value);
@@ -119,6 +117,22 @@ shaka.hls.Tag = class {
     return tagStr;
   }
 
+  /**
+   * Create the string key of the tag.
+   *
+   * @return {string}
+   */
+  getTagKey() {
+    const attributesToSkip = new Set()
+        .add('AUDIO')
+        .add('VIDEO')
+        .add('SUBTITLES')
+        .add('PATHWAY-ID')
+        .add('GROUP-ID')
+        .add('URI');
+    return this.toString(attributesToSkip);
+  }
+
   /**
    * Adds an attribute to an HLS Tag.
    *