Don't swap out the old RenderFrameHost until the new one commits.

content/browser/loader/cross_site_resource_handler.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_BROWSER_LOADER_CROSS_SITE_RESOURCE_HANDLER_H_
 #define CONTENT_BROWSER_LOADER_CROSS_SITE_RESOURCE_HANDLER_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "content/browser/loader/layered_resource_handler.h"
 #include "content/common/content_export.h"
 #include "net/url_request/url_request_status.h"
 
 namespace net {
 class URLRequest;
 }
 
 namespace content {
 
 struct TransitionLayerData;
 
-// Ensures that cross-site responses are delayed until the onunload handler of
-// the previous page is allowed to run.  This handler wraps an
-// AsyncEventHandler, and it sits inside SafeBrowsing and Buffered event
-// handlers.  This is important, so that it can intercept OnResponseStarted
-// after we determine that a response is safe and not a download.
+// Ensures that responses are delayed for navigations that must be transferred
+// to a different process.  This handler wraps an AsyncEventHandler, and it sits
+// inside SafeBrowsing and Buffered event handlers.  This is important, so that
+// it can intercept OnResponseStarted after we determine that a response is safe
+// and not a download.
 class CrossSiteResourceHandler : public LayeredResourceHandler {
  public:
   CrossSiteResourceHandler(scoped_ptr<ResourceHandler> next_handler,
                            net::URLRequest* request);
   virtual ~CrossSiteResourceHandler();
 
   // ResourceHandler implementation:
   virtual bool OnRequestRedirected(const net::RedirectInfo& redirect_info,
                                    ResourceResponse* response,
                                    bool* defer) OVERRIDE;
@@ skipping 16 matching lines @@
 
   // Navigations are deferred at OnResponseStarted to parse out any navigation
   // transition link headers, and give the navigation transition (if it exists)
   // a chance to run.
   void ResumeResponseDeferredAtStart(int request_id);
 
   // Returns whether the handler is deferred.
   bool did_defer_for_testing() const { return did_defer_; }
 
  private:
-  // Prepare to render the cross-site response in a new RenderViewHost, by
-  // telling the old RenderViewHost to run its onunload handler.
-  void StartCrossSiteTransition(ResourceResponse* response,
-                                bool should_transfer);
+  // Prepare to transfer the cross-site response to a new RenderFrameHost, by
+  // asking it to issue an identical request (on the UI thread).
+  void StartCrossSiteTransition(ResourceResponse* response);
 
   // Defer the navigation to the UI thread to check whether transfer is required
   // or not. Currently only used in --site-per-process.
   bool DeferForNavigationPolicyCheck(ResourceRequestInfoImpl* info,
                                      ResourceResponse* response,
                                      bool* defer);
 
   bool OnNavigationTransitionResponseStarted(
       ResourceResponse* response,
       bool* defer,
@@ skipping 22 matching lines @@
   // PostTaskAndReplyWithResult. If a transfer is needed, it goes back to the UI
   // thread. This can be removed once the code is changed to only do one hop.
   base::WeakPtrFactory<CrossSiteResourceHandler> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(CrossSiteResourceHandler);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_LOADER_CROSS_SITE_RESOURCE_HANDLER_H_