perf: Use navigator.userAgentData.platform to detect Android and Fuchsia (#8102)

More info: https://wicg.github.io/ua-client-hints/#sec-ch-ua-platform

Author: avelad

lib/util/platform.js

@@ -543,6 +543,9 @@ shaka.util.Platform = class {
    * @return {boolean}
    */
   static isAndroid() {
+    if (navigator.userAgentData && navigator.userAgentData.platform) {
+      return navigator.userAgentData.platform.toLowerCase() == 'android';
+    }
     return shaka.util.Platform.userAgentContains_('Android');
   }
 
@@ -552,6 +555,9 @@ shaka.util.Platform = class {
    * @return {boolean}
    */
   static isFuchsia() {
+    if (navigator.userAgentData && navigator.userAgentData.platform) {
+      return navigator.userAgentData.platform.toLowerCase() == 'fuchsia';
+    }
     return shaka.util.Platform.userAgentContains_('Fuchsia');
   }
 

test/polyfill/media_capabilities_unit.js

@@ -193,6 +193,8 @@ describe('MediaCapabilities', () => {
             pending('Unable to delete window.cast');
           }
 
+          spyOn(shaka['util']['Platform'], 'isAndroid').and.returnValue(false);
+
           const isChromecastSpy =
               spyOn(shaka['util']['Platform'],
                   'isChromecast').and.returnValue(true);
@@ -218,6 +220,7 @@ describe('MediaCapabilities', () => {
         async () => {
           // We only set the cast namespace, but not the canDisplayType() API.
           window['cast'] = {};
+          spyOn(shaka['util']['Platform'], 'isAndroid').and.returnValue(false);
           const isChromecastSpy =
               spyOn(shaka['util']['Platform'],
                   'isChromecast').and.returnValue(true);
@@ -247,6 +250,7 @@ describe('MediaCapabilities', () => {
       window['cast'] = {
         __platform__: {canDisplayType: mockCanDisplayType},
       };
+      spyOn(shaka['util']['Platform'], 'isAndroid').and.returnValue(false);
       const isChromecastSpy =
           spyOn(shaka['util']['Platform'],
               'isChromecast').and.returnValue(true);