feat: enable uninstalling PatchedMediaKeysApple (shaka-project#4471)

Close shaka-project#4469

AUTHORS

@@ -46,6 +46,7 @@ Jun Hong Chong <[email protected]>
 Jürgen Kartnaller <[email protected]>
 JW Player <*@jwplayer.com>
 Lucas Gabriel Sánchez <[email protected]>
+Martin Stark <[email protected]>
 Matthias Van Parijs <[email protected]>
 Mattias Wadman <[email protected]>
 Mohamed Rashid <[email protected]>

CONTRIBUTORS

@@ -73,6 +73,7 @@ Jun Hong Chong <[email protected]>
 Jürgen Kartnaller <[email protected]>
 Leandro Ribeiro Moreira <[email protected]>
 Lucas Gabriel Sánchez <[email protected]>
+Martin Stark <[email protected]>
 Matias Russitto <[email protected]>
 Matthias Van Parijs <[email protected]>
 Mattias Wadman <[email protected]>

docs/tutorials/fairplay.md

@@ -8,6 +8,13 @@ Modern EME yet, you can use legacy Apple Media Keys with:
 shaka.polyfill.PatchedMediaKeysApple.install();
 ```
 
+If you need to use both legacy and Modern EME, for example if you have to support
+multiple DRM providers, it is possible to enable uninstalling the polyfill:
+```js
+shaka.polyfill.PatchedMediaKeysApple.install(/* enableUninstall= */ true);
+shaka.polyfill.PatchedMediaKeysApple.uninstall();
+```
+
 The support in each case would be the following:
 
 |            |Modern EME |legacy Apple Media Keys|

lib/polyfill/patchedmediakeys_apple.js

@@ -27,14 +27,33 @@ goog.require('shaka.util.StringUtils');
 shaka.polyfill.PatchedMediaKeysApple = class {
   /**
    * Installs the polyfill if needed.
+   * @param {boolean} enableUninstall enables uninstalling the polyfill
    * @export
    */
-  static install() {
+  static install(enableUninstall = false) {
     if (!window.HTMLVideoElement || !window.WebKitMediaKeys) {
       // No HTML5 video or no prefixed EME.
       return;
     }
 
+    if (enableUninstall) {
+      this.enableUninstall = true;
+      this.originalHTMLMediaElementPrototypeMediaKeys =
+        /** @type {!Object} */ (
+          Object.getOwnPropertyDescriptor(
+              // eslint-disable-next-line no-restricted-syntax
+              HTMLMediaElement.prototype, 'mediaKeys',
+          )
+        );
+      // eslint-disable-next-line no-restricted-syntax
+      this.originalHTMLMediaElementPrototypeSetMediaKeys = HTMLMediaElement
+          .prototype.setMediaKeys;
+      this.originalWindowMediaKeys = window.MediaKeys;
+      this.originalWindowMediaKeySystemAccess = window.MediaKeySystemAccess;
+      this.originalNavigatorRequestMediaKeySystemAccess = navigator
+          .requestMediaKeySystemAccess;
+    }
+
     shaka.log.info('Using Apple-prefixed EME');
 
     // Alias
@@ -59,6 +78,41 @@ shaka.polyfill.PatchedMediaKeysApple = class {
     window.shakaMediaKeysPolyfill = true;
   }
 
+  /**
+   * Uninstalls the polyfill if needed and enabled.
+   * @export
+   */
+  static uninstall() {
+    if (!this.enableUninstall) {
+      return;
+    }
+
+    shaka.log.info('Un-installing Apple-prefixed EME');
+
+    this.enableUninstall = false;
+    Object.defineProperty(
+        // eslint-disable-next-line no-restricted-syntax
+        HTMLMediaElement.prototype,
+        'mediaKeys',
+        this.originalHTMLMediaElementPrototypeMediaKeys,
+    );
+    // eslint-disable-next-line no-restricted-syntax
+    HTMLMediaElement.prototype.setMediaKeys = this
+        .originalHTMLMediaElementPrototypeSetMediaKeys;
+    window.MediaKeys = this.originalWindowMediaKeys;
+    window.MediaKeySystemAccess = this.originalWindowMediaKeySystemAccess;
+    navigator.requestMediaKeySystemAccess = this
+        .originalNavigatorRequestMediaKeySystemAccess;
+
+    this.originalWindowMediaKeys = null;
+    this.originalWindowMediaKeySystemAccess = null;
+    this.originalHTMLMediaElementPrototypeSetMediaKeys = null;
+    this.originalNavigatorRequestMediaKeySystemAccess = null;
+    this.originalHTMLMediaElementPrototypeMediaKeys = null;
+
+    window.shakaMediaKeysPolyfill = false;
+  }
+
   /**
    * An implementation of navigator.requestMediaKeySystemAccess.
    * Retrieves a MediaKeySystemAccess object.

test/polyfill/patchedmediakeys_apple_unit.js

@@ -0,0 +1,124 @@
+describe('PatchedMediaKeys_Apple', () => {
+  const PatchedMediaKeysApple = shaka.polyfill.PatchedMediaKeysApple;
+  let originalMediaKeys;
+  let originalHTMLMediaElementPrototypeSetMediaKeys;
+  let originalWindowMediaKeys;
+  let originalWindowMediaKeySystemAccess;
+  let originalNavigatorRequestMediaKeySystemAccess;
+  let originalHTMLSVideoElement;
+  let originalWebKitMediaKeys;
+
+  beforeEach(() => {
+    originalHTMLSVideoElement = window.HTMLVideoElement;
+    originalWebKitMediaKeys = window.WebKitMediaKeys;
+
+    Object.defineProperty(window,
+        'HTMLVideoElement', {value: {}, configurable: true, writable: true});
+    Object.defineProperty(window,
+        'WebKitMediaKeys', {value: {}, configurable: true, writable: true});
+
+    originalMediaKeys = /** @type {!Object} */ (
+      Object.getOwnPropertyDescriptor(
+          // eslint-disable-next-line no-restricted-syntax
+          HTMLMediaElement.prototype, 'mediaKeys',
+      )
+    );
+
+    // eslint-disable-next-line no-restricted-syntax
+    originalHTMLMediaElementPrototypeSetMediaKeys = HTMLMediaElement
+        .prototype.setMediaKeys;
+    originalWindowMediaKeys = window.MediaKeys;
+    originalWindowMediaKeySystemAccess = window.MediaKeySystemAccess;
+    originalNavigatorRequestMediaKeySystemAccess = navigator
+        .requestMediaKeySystemAccess;
+
+    delete window.shakaMediaKeysPolyfill;
+  });
+
+  afterEach(() => {
+    window.HTMLVideoElement = originalHTMLSVideoElement;
+    window.WebKitMediaKeys = originalWebKitMediaKeys;
+
+    Object.defineProperty(
+        // eslint-disable-next-line no-restricted-syntax
+        HTMLMediaElement.prototype,
+        'mediaKeys',
+        originalMediaKeys,
+    );
+
+    // eslint-disable-next-line no-restricted-syntax
+    HTMLMediaElement
+        .prototype.setMediaKeys =
+        originalHTMLMediaElementPrototypeSetMediaKeys;
+    window.MediaKeys = originalWindowMediaKeys;
+    window.MediaKeySystemAccess = originalWindowMediaKeySystemAccess;
+    navigator
+        .requestMediaKeySystemAccess =
+      originalNavigatorRequestMediaKeySystemAccess;
+
+    delete window.shakaMediaKeysPolyfill;
+  });
+
+  describe('install', () => {
+    it('should override browser globals', () => {
+      shaka.polyfill.PatchedMediaKeysApple.install();
+
+      expect(shaka.polyfill.PatchedMediaKeysApple.enableUninstall)
+          .toBe(undefined);
+
+      expect(
+          originalHTMLMediaElementPrototypeSetMediaKeys,
+      ).not.toEqual(
+          // eslint-disable-next-line no-restricted-syntax
+          HTMLMediaElement.prototype.setMediaKeys,
+      );
+
+      expect(
+          Object.getOwnPropertyDescriptor(
+          // eslint-disable-next-line no-restricted-syntax
+              HTMLMediaElement.prototype, 'mediaKeys',
+          ).value,
+      ).toBeNull();
+
+      // eslint-disable-next-line no-restricted-syntax
+      expect(HTMLMediaElement.prototype.setMediaKeys)
+          .toEqual(PatchedMediaKeysApple.setMediaKeys);
+
+      expect(window.MediaKeys).toEqual(PatchedMediaKeysApple.MediaKeys);
+      expect(window.MediaKeySystemAccess)
+          .toEqual(PatchedMediaKeysApple.MediaKeySystemAccess);
+      expect(navigator.requestMediaKeySystemAccess)
+          .toEqual(PatchedMediaKeysApple.requestMediaKeySystemAccess);
+      expect(window.shakaMediaKeysPolyfill).toBe(true);
+    });
+  });
+
+  describe('uninstall', () => {
+    it('should restore browser globals', () => {
+      shaka.polyfill.PatchedMediaKeysApple.install(true);
+
+      expect(shaka.polyfill.PatchedMediaKeysApple.enableUninstall)
+          .toBe(true);
+
+      shaka.polyfill.PatchedMediaKeysApple.uninstall();
+
+      expect(
+          Object.getOwnPropertyDescriptor(
+          // eslint-disable-next-line no-restricted-syntax
+              HTMLMediaElement.prototype, 'mediaKeys',
+          ).value,
+      ).not.toBeNull();
+
+      // eslint-disable-next-line no-restricted-syntax
+      expect(HTMLMediaElement.prototype.setMediaKeys)
+          .toEqual(originalHTMLMediaElementPrototypeSetMediaKeys);
+
+      expect(window.MediaKeys).toEqual(originalWindowMediaKeys);
+      expect(window.MediaKeySystemAccess)
+          .toEqual(originalWindowMediaKeySystemAccess);
+      expect(navigator.requestMediaKeySystemAccess)
+          .toEqual(originalNavigatorRequestMediaKeySystemAccess);
+      expect(window.shakaMediaKeysPolyfill).toBe(false);
+    });
+  });
+});