feat(BrowserCapabilities): introduce isChromiumBased

This function helps simplify the code when handling browsers that are pretty
much Chrome in disguise.

modules/RTC/RTCUtils.js

 
             this.getStreamID = ({ id }) => id;
             this.getTrackID = ({ id }) => id;
-        } else if (browser.isChrome() // this is chrome < 61
-                || browser.isOpera()
-                || browser.isNWJS()
-                || browser.isElectron()
+        } else if (browser.isChromiumBased() // this is chrome < 61
                 || browser.isReactNative()) {
 
             this.RTCPeerConnectionType = RTCPeerConnection;
     _initPCConstraints(options) {
         if (browser.isFirefox()) {
             this.pcConstraints = {};
-        } else if (browser.isChrome()
-            || browser.isOpera()
-            || browser.isNWJS()
-            || browser.isElectron()
-            || browser.isReactNative()) {
+        } else if (browser.isChromiumBased() || browser.isReactNative()) {
             this.pcConstraints = { optional: [
                 { googHighStartBitrate: 0 },
                 { googPayloadPadding: true },
     isDeviceChangeAvailable(deviceType) {
         return deviceType === 'output' || deviceType === 'audiooutput'
             ? isAudioOutputDeviceChangeAvailable
-            : browser.isChrome()
-                || browser.isFirefox()
-                || browser.isOpera()
-                || browser.isNWJS()
-                || browser.isElectron()
-                || browser.isEdge();
+            : browser.isChromiumBased()
+                || browser.isFirefox() || browser.isEdge();
     }
 
     /**

modules/RTC/TraceablePeerConnection.js

     }
 
     // Bind 'addtrack'/'removetrack' event handlers
-    if (browser.isChrome() || browser.isNWJS()
-        || browser.isElectron() || browser.isEdge()) {
+    if (browser.isChromiumBased() || browser.isEdge()) {
         stream.onaddtrack = event => {
             this._remoteTrackAdded(stream, event.track);
         };

modules/browser/BrowserCapabilities.js

         return !this.isEdge() && !this.isFirefox();
     }
 
+    /**
+     * Checks if the current browser is Chromium based, that is, it's either
+     * Chrome / Chromium or uses it as its engine, but doesn't identify as
+     * Chrome.
+     *
+     * This includes the following browsers:
+     * - Chrome and Chromium
+     * - Other browsers which use the Chrome engine, but are detected as Chrome,
+     *   such as Brave and Vivaldi
+     * - Browsers which are NOT Chrome but use it as their engine, and have
+     *   custom detection code: Opera, Electron and NW.JS
+     */
+    isChromiumBased() {
+        return this.isChrome()
+            || this.isElectron()
+            || this.isNWJS()
+            || this.isOpera();
+    }
+
     /**
      * Checks if current browser is a Safari and a version of Safari that
      * supports native webrtc.
      * @returns {boolean} true if the browser is supported, false otherwise.
      */
     isSupported() {
-        return this.isChrome()
+        return this.isChromiumBased()
             || this.isEdge()
-            || this.isElectron()
             || this.isFirefox()
-            || this.isNWJS()
-            || this.isOpera()
             || this.isReactNative()
             || this.isSafariWithWebrtc();
     }
      * otherwise.
      */
     supportsVideoMuteOnConnInterrupted() {
-        return this.isChrome() || this.isElectron() || this.isReactNative();
+        return this.isChromiumBased() || this.isReactNative();
     }
 
     /**
      * @returns {boolean} true if they are supported, false otherwise.
      */
     supportsRtpStatistics() {
-        return this.isChrome()
+        return this.isChromiumBased()
             || this.isEdge()
-            || this.isElectron()
             || this.isFirefox()
-            || this.isNWJS()
-            || this.isOpera()
             || this.isReactNative()
             || this.isSafariWithWebrtc();
     }
      * candidates through the legacy getStats() API.
      */
     supportsLocalCandidateRttStatistics() {
-        return this.isChrome()
-            || this.isElectron()
-            || this.isReactNative();
+        return this.isChromiumBased() || this.isReactNative();
     }
 
     /**
      * @returns {boolean}
      */
     supportsSimulcast() {
-        return this.isChrome()
-            || this.isFirefox()
-            || this.isElectron()
-            || this.isNWJS()
-            || this.isReactNative();
+        return this.isChromiumBased()
+            || this.isFirefox() || this.isReactNative();
     }
 
     /**