Prevent duplicated callSurfaceChanged call when exiting immersive mode (#2961)

Author: MortimerGoro

app/src/common/shared/org/mozilla/vrbrowser/browser/engine/Session.java

@@ -544,6 +544,10 @@ public boolean hasCapturedBitmap() {
         return BitmapCache.getInstance(mContext).hasBitmap(mState.mId);
     }
 
+    public boolean hasDisplay() {
+        return mState != null && mState.mDisplay != null;
+    }
+
     public void purgeHistory() {
         if (mState.mSession != null) {
             mState.mSession.purgeHistory();

app/src/common/shared/org/mozilla/vrbrowser/ui/widgets/WindowWidget.java

@@ -314,7 +314,7 @@ public void onResume() {
         super.onResume();
         if (isVisible() || mIsInVRVideoMode) {
             mSession.setActive(true);
-            if (!SettingsStore.getInstance(getContext()).getLayersEnabled()) {
+            if (!SettingsStore.getInstance(getContext()).getLayersEnabled() && !mSession.hasDisplay()) {
                 // Ensure the Gecko Display is correctly recreated.
                 // See: https://github.com/MozillaReality/FirefoxReality/issues/2880
                 callSurfaceChanged();