PlzNavigate: Invoke didStartProvisionalLoad() when the renderer initiates a navigation in startLoad(

content/browser/frame_host/navigator_impl.cc

 // Copyright 2013 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/frame_host/navigator_impl.h"
 
 #include <utility>
 
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
@@ skipping 1225 matching lines @@
     NavigationHandleImpl* navigation_handle) {
   // If there is no browser-initiated pending entry for this navigation and it
   // is not for the error URL, create a pending entry using the current
   // SiteInstance, and ensure the address bar updates accordingly.  We don't
   // know the referrer or extra headers at this point, but the referrer will
   // be set properly upon commit.
   NavigationEntryImpl* pending_entry = controller_->GetPendingEntry();
   bool has_browser_initiated_pending_entry =
       pending_entry && !pending_entry->is_renderer_initiated();
 
+  // PlzNavigate
+  // A pending navigation entry is created in OnBeginNavigation(). The renderer
+  // sends a provisional load notification after that. We don't want to create
+  // a duplicate navigation entry here.
+  bool renderer_provisional_load_to_pending_url =
+      pending_entry && pending_entry->is_renderer_initiated() &&
+      (pending_entry->GetURL() == url);
+
   // If there is a transient entry, creating a new pending entry will result
   // in deleting it, which leads to inconsistent state.
   bool has_transient_entry = !!controller_->GetTransientEntry();
 
-  if (!has_browser_initiated_pending_entry && !has_transient_entry) {
+  if (!has_browser_initiated_pending_entry && !has_transient_entry &&
+      !renderer_provisional_load_to_pending_url) {
     std::unique_ptr<NavigationEntryImpl> entry =
         NavigationEntryImpl::FromNavigationEntry(
             controller_->CreateNavigationEntry(
                 url, content::Referrer(), ui::PAGE_TRANSITION_LINK,
                 true /* is_renderer_initiated */, std::string(),
                 controller_->GetBrowserContext()));
     entry->set_site_instance(site_instance);
     // TODO(creis): If there's a pending entry already, find a safe way to
     // update it instead of replacing it and copying over things like this.
     // That will allow us to skip the NavigationHandle update below as well.
@@ skipping 10 matching lines @@
     if (navigation_handle)
       navigation_handle->update_entry_id_for_transfer(entry->GetUniqueID());
 
     controller_->SetPendingEntry(std::move(entry));
     if (delegate_)
       delegate_->NotifyChangedNavigationState(content::INVALIDATE_TYPE_URL);
   }
 }
 
 }  // namespace content