feat: Add randomUUID polyfill (shaka-project#3669)

Related to: shaka-project#3662

build/types/polyfill

@@ -13,6 +13,7 @@
 +../../lib/polyfill/patchedmediakeys_nop.js
 +../../lib/polyfill/patchedmediakeys_webkit.js
 +../../lib/polyfill/pip_webkit.js
++../../lib/polyfill/random_uuid.js
 +../../lib/polyfill/storage_estimate.js
 +../../lib/polyfill/video_play_promise.js
 +../../lib/polyfill/videoplaybackquality.js

externs/webcrypto.js

@@ -0,0 +1,18 @@
+/*! @license
+ * Shaka Player
+ * Copyright 2016 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+
+/**
+ * @fileoverview Externs for crypto properties not in the Closure compiler.
+ *
+ * @externs
+ */
+
+
+/**
+ * @return {string}
+ */
+webCrypto.Crypto.prototype.randomUUID = function() {};

lib/polyfill/random_uuid.js

@@ -0,0 +1,52 @@
+/*! @license
+ * Shaka Player
+ * Copyright 2016 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+goog.provide('shaka.polyfill.RandomUUID');
+
+goog.require('shaka.log');
+goog.require('shaka.polyfill');
+
+/**
+ * @summary A polyfill to provide window.crypto.randomUUID in all browsers.
+ * @export
+ */
+shaka.polyfill.RandomUUID = class {
+  /**
+   * Install the polyfill if needed.
+   * @export
+   */
+  static install() {
+    shaka.log.debug('randomUUID.install');
+
+    if (!window.crypto) {
+      // See: https://caniuse.com/cryptography
+      shaka.log.debug(
+          'window.crypto must be available to install randomUUID polyfill.');
+      return;
+    }
+
+    if ('randomUUID' in window.crypto) {
+      shaka.log.debug(
+          'RandomUUID: Native window.crypto.randomUUID() support found.');
+      return;
+    }
+
+    window.crypto.randomUUID = shaka.polyfill.RandomUUID.randomUUID_;
+  }
+
+  /**
+   * @return {string}
+   * @private
+   */
+  static randomUUID_() {
+    const url = URL.createObjectURL(new Blob());
+    const uuid = url.toString();
+    URL.revokeObjectURL(url);
+    return uuid.substr(uuid.lastIndexOf('/') + 1);
+  }
+};
+
+
+shaka.polyfill.register(shaka.polyfill.RandomUUID.install);