PlzNavigate: fix timing issue in app window creation

content/public/browser/web_contents_observer.h

 // 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.
 
 #ifndef CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_OBSERVER_H_
 #define CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_OBSERVER_H_
 
 #include "base/process/kill.h"
 #include "base/process/process_handle.h"
 #include "content/common/content_export.h"
@@ skipping 103 matching lines @@
   // with another one, possibly changing processes. The RenderViewHost that has
   // been replaced is in |old_host|, which is nullptr if the old RVH was shut
   // down.
   virtual void RenderViewHostChanged(RenderViewHost* old_host,
                                      RenderViewHost* new_host) {}
 
   // Navigation related events ------------------------------------------------
 
   // Called when a navigation started in the WebContents. |navigation_handle|
   // is unique to a specific navigation. The same |navigation_handle| will be
-  // provided on subsequent calls to DidRedirect/Commit/FinishNavigation
-  // related to this navigation.
+  // provided on subsequent calls to
+  // DidRedirect/Commit/FinishNavigation/ReadyToCommitNavigation related to
+  // this navigation.
   //
   // Note that this is fired by navigations in any frame of the WebContents,
   // not just the main frame.
   //
   // Note that more than one navigation can be ongoing in the same frame at the
   // same time (including the main frame). Each will get its own
   // NavigationHandle.
   //
   // Note that there is no guarantee that DidFinishNavigation will be called
   // for any particular navigation before DidStartNavigation is called on the
   // next.
   virtual void DidStartNavigation(NavigationHandle* navigation_handle) {}
 
   // Called when a navigation encountered a server redirect.
   virtual void DidRedirectNavigation(NavigationHandle* navigation_handle) {}
 
+  // PlzNavigate
+  // Called when the navigation is ready to be committed in a renderer. This is
+  // the first point in time where a RenderFrameHost is associated with the
+  // navigation. Observers that want to initialize any renderer side
+  // structures/state before the RenderFrame is navigated, should use this
+  // method as opposed to DidCommitNavigation, which is after the fact.
+  virtual void ReadyToCommitNavigation(NavigationHandle* navigation_handle) {}
+
   // Called when a navigation was committed.
   virtual void DidCommitNavigation(NavigationHandle* navigation_handle) {}
 
   // Called when a navigation stopped in the WebContents. This happens when a
   // navigation is either aborted, replaced by a new one, or the document load
   // finishes. Note that |navigation_handle| will be destroyed at the end of
   // this call, so do not keep a reference to it afterward.
   virtual void DidFinishNavigation(NavigationHandle* navigation_handle) {}
 
   // ---------------------------------------------------------------------------
@@ skipping 292 matching lines @@
   void ResetWebContents();
 
   WebContentsImpl* web_contents_;
 
   DISALLOW_COPY_AND_ASSIGN(WebContentsObserver);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_OBSERVER_H_