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;

[Charlie Reis, 2017/06/28 17:05:22]

nit: Please include a comment saying that we should not call GetProcess() if
HasProcess() returns false, since we don't want to trigger a process creation.

[clamy, 2017/06/30 15:13:00]

Done.

+  speculative_site_instance_ =
+      site_instance->HasProcess() ? site_instance : nullptr;
+
   // 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