Prevent possible crash unregistering VR BroadcastReceiver

chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java

Index: chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java b/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java
index a6b95d0bbad074ebf4f62a7a6f8777136179223b..12629870dc2b0462e70aff9eee2dc6f36bbbee66 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java
@@ -157,7 +157,11 @@ public class VrShellDelegate implements ApplicationStatus.ActivityStateListener,
         public void unregister() {
             ChromeActivity activity = mTargetActivity.get();
             if (activity == null) return;
-            activity.unregisterReceiver(VrBroadcastReceiver.this);
+            try {
+                activity.unregisterReceiver(VrBroadcastReceiver.this);
+            } catch (IllegalArgumentException e) {
+                // Ignore this. This means our receiver was already unregistered somehow.
+            }
         }
     }