feat(MediaCap): make StreamUtils.filterManifest async

Player.filterManifest() does two things:
1. Filter the manifest with Drm, codecs and currentVariant's
   compatibility in StreamUtil.
2. Filter the manifest with PlayerConfiguration.restrictions.

In applyConfig_(), only the restrictions config affects filtering
the manifests. We don't need to call StreamUtils.filterManifest().

2. Make the filterManifest function async.

Issue #1391

Change-Id: I2fba9cabb3f3a3e89f5d990c4eeb19cc74924de9

lib/player.js

@@ -1745,7 +1745,7 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
 
     // Now that we have drm information, filter the manifest (again) so that we
     // can ensure we only use variants with the selected key system.
-    this.filterManifest_(this.manifest_);
+    await this.filterManifest_(this.manifest_);
   }
 
   /**
@@ -1908,7 +1908,8 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
     }
 
     // Re-filter the manifest after streams have been chosen.
-    this.filterManifest_(this.manifest_);
+    await this.filterManifest_(this.manifest_);
+
     // Dispatch a 'trackschanged' event now that all initial filtering is done.
     this.onTracksChanged_();
     // Since the first streams just became active, send an adaptation event.
@@ -2727,8 +2728,8 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
 
       // Need to apply the restrictions.
       try {
-        // this.filterManifest_() may throw.
-        this.filterManifest_(this.manifest_);
+        // this.filterManifestWithRestrictions_() may throw.
+        this.filterManifestWithRestrictions_(this.manifest_);
       } catch (error) {
         this.onError_(error);
       }
@@ -4493,19 +4494,29 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
    * @param {?shaka.extern.Manifest} manifest
    * @private
    */
-  filterManifest_(manifest) {
+  async filterManifest_(manifest) {
+    await this.filterManifestWithStreamUtils_(manifest);
+    this.filterManifestWithRestrictions_(manifest);
+  }
+
+  /**
+   * Filters a manifest, removing unplayable streams/variants.
+   *
+   * @param {?shaka.extern.Manifest} manifest
+   * @private
+   */
+  async filterManifestWithStreamUtils_(manifest) {
     goog.asserts.assert(manifest, 'Manifest should exist!');
     goog.asserts.assert(this.video_, 'Must not be destroyed');
-    const StreamUtils = shaka.util.StreamUtils;
 
     /** @type {?shaka.extern.Variant} */
     const currentVariant = this.streamingEngine_ ?
         this.streamingEngine_.getCurrentVariant() : null;
 
-    StreamUtils.filterManifest(
+    await shaka.util.StreamUtils.filterManifest(
         this.drmEngine_, currentVariant, manifest);
 
-    const valid = manifest.variants.some(StreamUtils.isPlayable);
+    const valid = manifest.variants.some(shaka.util.StreamUtils.isPlayable);
 
     // If none of the variants are playable, throw
     // CONTENT_UNSUPPORTED_BY_BROWSER.
@@ -4515,7 +4526,17 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
           shaka.util.Error.Category.MANIFEST,
           shaka.util.Error.Code.CONTENT_UNSUPPORTED_BY_BROWSER);
     }
+  }
 
+
+  /**
+   * Apply the restrictions configuration to the manifest, and check if there's
+   * a variant that meets the restrictions.
+   *
+   * @param {?shaka.extern.Manifest} manifest
+   * @private
+   */
+  filterManifestWithRestrictions_(manifest) {
     const tracksChanged = shaka.util.StreamUtils.applyRestrictions(
         manifest.variants, this.config_.restrictions, this.maxHwRes_);
     if (tracksChanged && this.streamingEngine_) {

lib/util/stream_utils.js

@@ -194,7 +194,7 @@ shaka.util.StreamUtils = class {
    * @param {?shaka.extern.Variant} currentVariant
    * @param {shaka.extern.Manifest} manifest
    */
-  static filterManifest(drmEngine, currentVariant, manifest) {
+  static async filterManifest(drmEngine, currentVariant, manifest) {
     const StreamUtils = shaka.util.StreamUtils;
 
     // Filter variants.
@@ -260,6 +260,9 @@ shaka.util.StreamUtils = class {
 
       return keep;
     });
+
+    // TODO: remove this after adopting MediaCapabilities.
+    await Promise.resolve();
   }