PlzNavigate: fix timing issue in app window creation

content/browser/web_contents/web_contents_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/web_contents/web_contents_impl.h"
 
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/lazy_instance.h"
@@ skipping 2770 matching lines @@
   FOR_EACH_OBSERVER(WebContentsObserver, observers_,
                     DidStartNavigation(navigation_handle));
 }
 
 void WebContentsImpl::DidRedirectNavigation(
     NavigationHandle* navigation_handle) {
   FOR_EACH_OBSERVER(WebContentsObserver, observers_,
                     DidRedirectNavigation(navigation_handle));
 }
 
+void WebContentsImpl::AboutToCommitNavigation(
+    NavigationHandle* navigation_handle) {
+  FOR_EACH_OBSERVER(WebContentsObserver, observers_,
+                    AboutToCommitNavigation(navigation_handle));
+}
+
 void WebContentsImpl::DidCommitNavigation(NavigationHandle* navigation_handle) {
   FOR_EACH_OBSERVER(WebContentsObserver, observers_,
                     DidCommitNavigation(navigation_handle));
 }
 
 void WebContentsImpl::DidFinishNavigation(NavigationHandle* navigation_handle) {
   FOR_EACH_OBSERVER(WebContentsObserver, observers_,
                     DidFinishNavigation(navigation_handle));
 }
 
@@ skipping 1826 matching lines @@
   return NULL;
 }
 
 void WebContentsImpl::SetForceDisableOverscrollContent(bool force_disable) {
   force_disable_overscroll_content_ = force_disable;
   if (view_)
     view_->SetOverscrollControllerEnabled(CanOverscrollContent());
 }
 
 }  // namespace content