--- a/mobile/android/geckoview/src/androidTest/java/org/mozilla/geckoview/test/TestRunnerActivity.java
+++ b/mobile/android/geckoview/src/androidTest/java/org/mozilla/geckoview/test/TestRunnerActivity.java
@@ -88,17 +88,16 @@ public class TestRunnerActivity extends 
 
             // We can't use e10s because we get deadlocked when quickly creating and
             // destroying sessions. Bug 1348361.
             settings.setBoolean(GeckoSessionSettings.USE_MULTIPROCESS, false);
         }
 
         final GeckoSession session = new GeckoSession(settings);
         session.setNavigationDelegate(mNavigationDelegate);
-        session.openWindow(this);
         return session;
     }
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
 
         Intent intent = getIntent();
@@ -106,16 +105,17 @@ public class TestRunnerActivity extends 
 
         final String intentArgs = intent.getStringExtra("args");
         final String args = intentArgs != null ? "-purgecaches " + intentArgs : "-purgecaches";
         GeckoSession.preload(this, args, false /* no multiprocess, see below */);
 
         // We can't use e10s because we get deadlocked when quickly creating and
         // destroying sessions. Bug 1348361.
         mSession = createSession();
+        mSession.openWindow(this);
 
         // If we were passed a URI in the Intent, open it
         final Uri uri = intent.getData();
         if (uri != null) {
             mSession.loadUri(uri);
         }
 
         mView = new GeckoView(this);

--- a/mobile/android/geckoview/src/main/java/org/mozilla/geckoview/GeckoSession.java
+++ b/mobile/android/geckoview/src/main/java/org/mozilla/geckoview/GeckoSession.java
@@ -146,21 +146,27 @@ public class GeckoSession extends LayerS
                         delegate.onLoadUri(GeckoSession.this, uri, where);
                     callback.sendSuccess(result);
                 } else if ("GeckoView:OnNewSession".equals(event)) {
                     final String uri = message.getString("uri");
                     delegate.onNewSession(GeckoSession.this, uri,
                         new Response<GeckoSession>() {
                             @Override
                             public void respond(GeckoSession session) {
-                                if (session != null && session.isOpen() && session.isReady()) {
-                                    throw new IllegalArgumentException("Must use a new GeckoSession instance");
+                                if (session == null) {
+                                    callback.sendSuccess(null);
+                                    return;
                                 }
 
-                                callback.sendSuccess(session != null ? session.getId() : null);
+                                if (session.isOpen()) {
+                                    throw new IllegalArgumentException("Must use an unopened GeckoSession instance");
+                                }
+
+                                session.openWindow(null);
+                                callback.sendSuccess(session.getId());
                             }
                         });
                 }
             }
         };
 
     private final GeckoSessionHandler<ProgressDelegate> mProgressHandler =
         new GeckoSessionHandler<ProgressDelegate>(