Preparation steps for adding speculative renderer creation.

content/browser/site_instance_impl.cc

 // 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.
 
 #include "content/browser/site_instance_impl.h"
 
 #include "base/command_line.h"
 #include "content/browser/browsing_instance.h"
 #include "content/browser/child_process_security_policy_impl.h"
 #include "content/browser/frame_host/debug_urls.h"
@@ skipping 123 matching lines @@
 
 void SiteInstanceImpl::SetSite(const GURL& url) {
   TRACE_EVENT2("navigation", "SiteInstanceImpl::SetSite",
                "site id", id_, "url", url.possibly_invalid_spec());
   // A SiteInstance's site should not change.
   // TODO(creis): When following links or script navigations, we can currently
   // render pages from other sites in this SiteInstance.  This will eventually
   // be fixed, but until then, we should still not set the site of a
   // SiteInstance more than once.
   DCHECK(!has_site_);
+  DCHECK(!browsing_instance_->HasSiteInstance(url));

[Charlie Reis, 2014/11/26 01:06:40]

I think this can fail, right?  See the comment in
BrowsingInstance::RegisterSiteInstance.

That will likely change in my planned SiteInstance site URL changes, but I'm not
sure it makes sense to add this until then.

[carlosk, 2014/11/27 11:02:44]

Yes, you are right. I had read that note but later on I assumed this was an
error case. Removed.

 
   // Remember that this SiteInstance has been used to load a URL, even if the
   // URL is invalid.
   has_site_ = true;
   BrowserContext* browser_context = browsing_instance_->browser_context();
   site_ = GetSiteForURL(browser_context, url);
 
   // Now that we have a site, register it with the BrowsingInstance.  This
   // ensures that we won't create another SiteInstance for this site within
   // the same BrowsingInstance, because all same-site pages within a
@@ skipping 191 matching lines @@
       *base::CommandLine::ForCurrentProcess();
   if (command_line.HasSwitch(switches::kEnableStrictSiteIsolation) ||
       command_line.HasSwitch(switches::kSitePerProcess)) {
     ChildProcessSecurityPolicyImpl* policy =
         ChildProcessSecurityPolicyImpl::GetInstance();
     policy->LockToOrigin(process_->GetID(), site_);
   }
 }
 
 }  // namespace content