move second vrdisplayactivate back to attachedCallback to fix auto enter VR issues, event being added too late, regressed in camera system prioritization patch (#4155)

Author: ngokevin

src/core/scene/a-scene.js

@@ -93,6 +93,34 @@ module.exports.AScene = registerElement('a-scene', {
         initMetaTags(this);
         initWakelock(this);
 
+        // Handler to exit VR (e.g., Oculus Browser back button).
+        this.onVRPresentChangeBound = bind(this.onVRPresentChange, this);
+        window.addEventListener('vrdisplaypresentchange', this.onVRPresentChangeBound);
+
+        // Bind functions.
+        this.enterVRBound = function () { self.enterVR(); };
+        this.exitVRBound = function () { self.exitVR(); };
+        this.exitVRTrueBound = function () { self.exitVR(true); };
+        this.pointerRestrictedBound = function () { self.pointerRestricted(); };
+        this.pointerUnrestrictedBound = function () { self.pointerUnrestricted(); };
+
+        if (!isWebXRAvailable) {
+          // Exit VR on `vrdisplaydeactivate` (e.g. taking off Rift headset).
+          window.addEventListener('vrdisplaydeactivate', this.exitVRBound);
+
+          // Exit VR on `vrdisplaydisconnect` (e.g. unplugging Rift headset).
+          window.addEventListener('vrdisplaydisconnect', this.exitVRTrueBound);
+
+          // Register for mouse restricted events while in VR
+          // (e.g. mouse no longer available on desktop 2D view)
+          window.addEventListener('vrdisplaypointerrestricted', this.pointerRestrictedBound);
+
+          // Register for mouse unrestricted events while in VR
+          // (e.g. mouse once again available on desktop 2D view)
+          window.addEventListener('vrdisplaypointerunrestricted',
+                                  this.pointerUnrestrictedBound);
+        }
+
         // Camera set up by camera system.
         this.addEventListener('cameraready', function () {
           self.attachedCallbackPostCamera();
@@ -125,36 +153,6 @@ module.exports.AScene = registerElement('a-scene', {
 
         // Add to scene index.
         scenes.push(this);
-
-        // Handler to exit VR (e.g., Oculus Browser back button).
-        this.onVRPresentChangeBound = bind(this.onVRPresentChange, this);
-        window.addEventListener('vrdisplaypresentchange', this.onVRPresentChangeBound);
-
-        // bind functions
-        this.enterVRBound = function () { self.enterVR(); };
-        this.exitVRBound = function () { self.exitVR(); };
-        this.exitVRTrueBound = function () { self.exitVR(true); };
-        this.pointerRestrictedBound = function () { self.pointerRestricted(); };
-        this.pointerUnrestrictedBound = function () { self.pointerUnrestricted(); };
-
-        if (!isWebXRAvailable) {
-          // Enter VR on `vrdisplayactivate` (e.g. putting on Rift headset).
-          window.addEventListener('vrdisplayactivate', this.enterVRBound);
-
-          // Exit VR on `vrdisplaydeactivate` (e.g. taking off Rift headset).
-          window.addEventListener('vrdisplaydeactivate', this.exitVRBound);
-
-          // Exit VR on `vrdisplaydisconnect` (e.g. unplugging Rift headset).
-          window.addEventListener('vrdisplaydisconnect', this.exitVRTrueBound);
-
-          // Register for mouse restricted events while in VR
-          // (e.g. mouse no longer available on desktop 2D view)
-          window.addEventListener('vrdisplaypointerrestricted', this.pointerRestrictedBound);
-
-          // Register for mouse unrestricted events while in VR
-          // (e.g. mouse once again available on desktop 2D view)
-          window.addEventListener('vrdisplaypointerunrestricted', this.pointerUnrestrictedBound);
-        }
       },
       writable: window.debug
     },