PlzNavigate: implement REUSE_COMMITTED_OR_PENDING_SITE for redirects

content/browser/frame_host/navigation_request.cc

 // 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.
 
 #include "content/browser/frame_host/navigation_request.h"
 
 #include <utility>
 
 #include "base/memory/ptr_util.h"
 #include "content/browser/appcache/appcache_navigation_handle.h"
@@ skipping 535 matching lines @@
     source_site_instance()->GetProcess()->FilterURL(false, &url);
     // FilterURL sets the URL to about:blank if the CSP checks prevent the
     // renderer from accessing it.
     if ((url == url::kAboutBlankURL) && (url != common_params_.url)) {
       navigation_handle_->set_net_error_code(net::ERR_ABORTED);
       frame_tree_node_->ResetNavigationRequest(false, true);
       return;
     }
   }
 
+  // Compute the SiteInstance to use for the redirect and pass its
+  // RenderProcessHost if it has a process. Keep a reference if it has a
+  // process, so that the SiteInstance and its associated process aren't deleted
+  // before the navigation is ready to commit.
+  scoped_refptr<SiteInstance> site_instance =
+      frame_tree_node_->render_manager()->GetSiteInstanceForNavigationRequest(
+          *this);
+  RenderProcessHost* expected_process =
+      site_instance->HasProcess() ? site_instance->GetProcess() : nullptr;
+  speculative_site_instance_ =
+      site_instance->HasProcess() ? site_instance : nullptr;

[clamy, 2017/06/27 16:43:32]

Note: I'm not storing the SiteInstance if its process is not initialized,
because I'm worried that someone could carelessly call GetProcess on it and
trigger an unwanted process initialization. Since we don't need to keep its
process alive (the motivation for storing it), I'd rather we don;t store it in
that case.

[Charlie Reis, 2017/06/27 18:46:34]

Acknowledged.

+
   // It's safe to use base::Unretained because this NavigationRequest owns the
   // NavigationHandle where the callback will be stored.
   bool is_external_protocol =
       !GetContentClient()->browser()->IsHandledURL(common_params_.url);
   navigation_handle_->WillRedirectRequest(
       common_params_.url, common_params_.method, common_params_.referrer.url,
       is_external_protocol, response->head.headers,
-      response->head.connection_info,
+      response->head.connection_info, expected_process,
       base::Bind(&NavigationRequest::OnRedirectChecksComplete,
                  base::Unretained(this)));
 }
 
 void NavigationRequest::OnResponseStarted(
     const scoped_refptr<ResourceResponse>& response,
     std::unique_ptr<StreamHandle> body,
     mojo::ScopedDataPipeConsumerHandle consumer_handle,
     const SSLStatus& ssl_status,
     std::unique_ptr<NavigationData> navigation_data,
@@ skipping 415 matching lines @@
           CSPDirective::FrameSrc, common_params_.url, is_redirect,
           common_params_.source_location.value_or(SourceLocation()),
           CSPContext::CHECK_ENFORCED_CSP)) {
     return CONTENT_SECURITY_POLICY_CHECK_PASSED;
   }
 
   return CONTENT_SECURITY_POLICY_CHECK_FAILED;
 }
 
 }  // namespace content