PlzNavigate: implement REUSE_COMMITTED_OR_PENDING_SITE for redirects

content/browser/frame_host/navigation_request.h

 // Copyright 2014 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_BROWSER_FRAME_HOST_NAVIGATION_REQUEST_H_
 #define CONTENT_BROWSER_FRAME_HOST_NAVIGATION_REQUEST_H_
 
 #include <memory>
 
 #include "base/callback_forward.h"
@@ skipping 251 matching lines @@
   int bindings_;
   int nav_entry_id_ = 0;
 
   // Whether the navigation should be sent to a renderer a process. This is
   // true, except for 204/205 responses and downloads.
   bool response_should_be_rendered_;
 
   // The type of SiteInstance associated with this navigation.
   AssociatedSiteInstanceType associated_site_instance_type_;
 
+  // Stores the SiteInstance created on redirects to check if there is an
+  // existing RenderProcessHost that can commit the navigation so that the
+  // renderer process is not deleted while the navigation is ongoing. If the
+  // SiteInstance was a brand new SiteInstance, it is not stored.
+  scoped_refptr<SiteInstance> speculative_site_instance_;
+
   // Whether the request may be transferred to a different process upon commit.
   // True for browser-initiated navigations and renderer-inititated navigations
   // started via the OpenURL path.
   // Note: the RenderFrameHostManager may still decide to have the navigation
   // commit in a different renderer process if it detects that a renderer
   // transfer is needed. This is the case in particular when --site-per-process
   // is enabled.
   bool may_transfer_;
 
   std::unique_ptr<NavigationHandleImpl> navigation_handle_;
@@ skipping 12 matching lines @@
   mojom::URLLoaderFactoryPtrInfo subresource_loader_factory_info_;
 
   base::WeakPtrFactory<NavigationRequest> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(NavigationRequest);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_NAVIGATION_REQUEST_H_