fix(TPC) Enable L1T3 for p2p streams (#2845)

* fix(TPC) Enable L1T3 for p2p streams

* squash: Update unit tests

modules/RTC/TPCUtils.js

      * @returns {Array<VideoEncoderScalabilityMode> | undefined}
      */
     calculateEncodingsScalabilityMode(localVideoTrack, codec, maxHeight) {
-        if (!this.pc.isSpatialScalabilityOn() || !this.codecSettings[codec].scalabilityModeEnabled) {
+        if (!this.codecSettings[codec].scalabilityModeEnabled) {
             return;
         }
 
+        // Use LIT3 for P2P wherever its supported.
+        if (!this.pc.isSpatialScalabilityOn()) {
+            return [ VideoEncoderScalabilityMode.L1T3 ];
+        }
+
         // Default modes for simulcast.
         const scalabilityModes = [
             VideoEncoderScalabilityMode.L1T3,

modules/RTC/TPCUtils.spec.js

                 expect(maxBitrates[0]).toBe(2500000);
 
                 scalabilityModes = tpcUtils.calculateEncodingsScalabilityMode(track, codec, height);
-                expect(scalabilityModes).toBe(undefined);
+                expect(scalabilityModes).toEqual([ VideoEncoderScalabilityMode.L1T3 ]);
 
                 scaleFactor = tpcUtils.calculateEncodingsScaleFactor(track, codec, height);
                 expect(scaleFactor[0]).toBe(SIM_LAYERS[2].scaleFactor);
                 expect(maxBitrates[0]).toBe(1000000);
 
                 scalabilityModes = tpcUtils.calculateEncodingsScalabilityMode(track, codec, height);
-                expect(scalabilityModes).toBe(undefined);
+                expect(scalabilityModes).toEqual([ VideoEncoderScalabilityMode.L1T3 ]);
 
                 scaleFactor = tpcUtils.calculateEncodingsScaleFactor(track, codec, height);
                 expect(scaleFactor[0]).toBe(SIM_LAYERS[2].scaleFactor);
                 expect(maxBitrates[0]).toBe(300000);
 
                 scalabilityModes = tpcUtils.calculateEncodingsScalabilityMode(track, codec, height);
-                expect(scalabilityModes).toBe(undefined);
+                expect(scalabilityModes).toEqual([ VideoEncoderScalabilityMode.L1T3 ]);
 
                 scaleFactor = tpcUtils.calculateEncodingsScaleFactor(track, codec, height);
                 expect(scaleFactor[0]).toBe(SIM_LAYERS[1].scaleFactor);
                 expect(maxBitrates[0]).toBe(1000000);
 
                 scalabilityModes = tpcUtils.calculateEncodingsScalabilityMode(track, codec, height);
-                expect(scalabilityModes).toBe(undefined);
+                expect(scalabilityModes).toEqual([ VideoEncoderScalabilityMode.L1T3 ]);
 
                 scaleFactor = tpcUtils.calculateEncodingsScaleFactor(track, codec, height);
                 expect(scaleFactor[0]).toBe(SIM_LAYERS[2].scaleFactor);
                 expect(maxBitrates[0]).toBe(100000);
 
                 scalabilityModes = tpcUtils.calculateEncodingsScalabilityMode(track, codec, height);
-                expect(scalabilityModes).toBe(undefined);
+                expect(scalabilityModes).toEqual([ VideoEncoderScalabilityMode.L1T3 ]);
 
                 scaleFactor = tpcUtils.calculateEncodingsScaleFactor(track, codec, height);
                 expect(scaleFactor[0]).toBe(SIM_LAYERS[0].scaleFactor);
                 expect(maxBitrates[0]).toBe(2500000);
 
                 scalabilityModes = tpcUtils.calculateEncodingsScalabilityMode(track, codec, height);
-                expect(scalabilityModes).toBe(undefined);
+                expect(scalabilityModes).toEqual([ VideoEncoderScalabilityMode.L1T3 ]);
 
                 scaleFactor = tpcUtils.calculateEncodingsScaleFactor(track, codec, height);
                 expect(scaleFactor[0]).toBe(SIM_LAYERS[2].scaleFactor);
                 expect(maxBitrates[0]).toBe(1200000);
 
                 scalabilityModes = tpcUtils.calculateEncodingsScalabilityMode(track, codec, height);
-                expect(scalabilityModes).toBe(undefined);
+                expect(scalabilityModes).toEqual([ VideoEncoderScalabilityMode.L1T3 ]);
 
                 scaleFactor = tpcUtils.calculateEncodingsScaleFactor(track, codec, height);
                 expect(scaleFactor[0]).toBe(SIM_LAYERS[2].scaleFactor);
                 expect(maxBitrates[0]).toBe(300000);
 
                 scalabilityModes = tpcUtils.calculateEncodingsScalabilityMode(track, codec, height);
-                expect(scalabilityModes).toBe(undefined);
+                expect(scalabilityModes).toEqual([ VideoEncoderScalabilityMode.L1T3 ]);
 
                 scaleFactor = tpcUtils.calculateEncodingsScaleFactor(track, codec, height);
                 expect(scaleFactor[0]).toBe(SIM_LAYERS[1].scaleFactor);
                 expect(maxBitrates[0]).toBe(100000);
 
                 scalabilityModes = tpcUtils.calculateEncodingsScalabilityMode(track, codec, height);
-                expect(scalabilityModes).toBe(undefined);
+                expect(scalabilityModes).toEqual([ VideoEncoderScalabilityMode.L1T3 ]);
 
                 scaleFactor = tpcUtils.calculateEncodingsScaleFactor(track, codec, height);
                 expect(scaleFactor[0]).toBe(SIM_LAYERS[0].scaleFactor);
                 expect(maxBitrates[0]).toBe(2500000);
 
                 scalabilityModes = tpcUtils.calculateEncodingsScalabilityMode(track, codec, height);
-                expect(scalabilityModes).toBe(undefined);
+                expect(scalabilityModes).toEqual([ VideoEncoderScalabilityMode.L1T3 ]);
 
                 scaleFactor = tpcUtils.calculateEncodingsScaleFactor(track, codec, height);
                 expect(scaleFactor[0]).toBe(SIM_LAYERS[2].scaleFactor);
                 expect(maxBitrates[0]).toBe(2000000);
 
                 scalabilityModes = tpcUtils.calculateEncodingsScalabilityMode(track, codec, height);
-                expect(scalabilityModes).toBe(undefined);
+                expect(scalabilityModes).toEqual([ VideoEncoderScalabilityMode.L1T3 ]);
 
                 scaleFactor = tpcUtils.calculateEncodingsScaleFactor(track, codec, height);
                 expect(scaleFactor[0]).toBe(SIM_LAYERS[2].scaleFactor);
                 expect(maxBitrates[0]).toBe(800000);
 
                 scalabilityModes = tpcUtils.calculateEncodingsScalabilityMode(track, codec, height);
-                expect(scalabilityModes).toBe(undefined);
+                expect(scalabilityModes).toEqual([ VideoEncoderScalabilityMode.L1T3 ]);
 
                 scaleFactor = tpcUtils.calculateEncodingsScaleFactor(track, codec, height);
                 expect(scaleFactor[0]).toBe(SIM_LAYERS[1].scaleFactor);
                 expect(maxBitrates[0]).toBe(400000);
 
                 scalabilityModes = tpcUtils.calculateEncodingsScalabilityMode(track, codec, height);
-                expect(scalabilityModes).toBe(undefined);
+                expect(scalabilityModes).toEqual([ VideoEncoderScalabilityMode.L1T3 ]);
 
                 scaleFactor = tpcUtils.calculateEncodingsScaleFactor(track, codec, height);
                 expect(scaleFactor[0]).toBe(SIM_LAYERS[0].scaleFactor);
                 expect(maxBitrates[0]).toBe(2500000);
 
                 scalabilityModes = tpcUtils.calculateEncodingsScalabilityMode(track, codec, height);
-                expect(scalabilityModes).toBe(undefined);
+                expect(scalabilityModes).toEqual([ VideoEncoderScalabilityMode.L1T3 ]);
 
                 scaleFactor = tpcUtils.calculateEncodingsScaleFactor(track, codec, height);
                 expect(scaleFactor[0]).toBe(SIM_LAYERS[2].scaleFactor);