Remove invalid check

extensions/browser/app_window/app_window.cc

Index: extensions/browser/app_window/app_window.cc
diff --git a/extensions/browser/app_window/app_window.cc b/extensions/browser/app_window/app_window.cc
index 67c5019fed46c095e8be287eeb014e22f6758626..cee54392ed9a1b388eb6518cebe6e478106169bd 100644
--- a/extensions/browser/app_window/app_window.cc
+++ b/extensions/browser/app_window/app_window.cc
@@ -484,7 +484,14 @@ void AppWindow::SetOnFirstCommitCallback(const base::Closure& callback) {
 }
 
 void AppWindow::OnReadyToCommitFirstNavigation() {
-  CHECK(content::IsBrowserSideNavigationEnabled());
+  if (!content::IsBrowserSideNavigationEnabled())
+    return;
+
+  // PlzNavigate: execute renderer-side setup now that there is a renderer
+  // process assigned to the navigation. With renderer-side navigation, this
+  // would happen before the navigation starts, but PlzNavigate must wait until
+  // this point in time in the navigation.
+
   WindowEventsReady();
   if (on_first_commit_callback_.is_null())
     return;