"Top Document Isolation" mode

content/browser/browsing_instance.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/browsing_instance.h"
 
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "content/browser/site_instance_impl.h"
 #include "content/public/browser/browser_context.h"
@@ skipping 18 matching lines @@
 
 SiteInstance* BrowsingInstance::GetSiteInstanceForURL(const GURL& url) {
   std::string site =
       SiteInstanceImpl::GetSiteForURL(browser_context_, url)
           .possibly_invalid_spec();
 
   SiteInstanceMap::iterator i = site_instance_map_.find(site);
   if (i != site_instance_map_.end())
     return i->second;
 
-
   // No current SiteInstance for this site, so let's create one.
   SiteInstanceImpl* instance = new SiteInstanceImpl(this);
 
   // Set the site of this new SiteInstance, which will register it with us.
   instance->SetSite(url);
   return instance;
 }
 
+SiteInstance* BrowsingInstance::GetSiteInstanceForThirdPartySubframes(
+    const GURL& url) {
+  // If we already have a site instance for this site, always use it instead
+  // of the site instance for third party subframes.
+  if (HasSiteInstance(url))

[Charlie Reis, 2016/03/18 21:15:13]

I'm going to suggest skipping this.  Don't worry about breaking the script
connections to preexisting main frames, at least for the time being.  It would
be unusual for the subframe to depend on such a window existing.

+    return GetSiteInstanceForURL(url);
+
+  if (!site_instance_for_third_party_subframes_) {
+    SiteInstanceImpl* instance = new SiteInstanceImpl(this);
+    instance->set_is_for_third_party_subframes();
+    instance->SetSite(url);
+    site_instance_for_third_party_subframes_ = instance;
+  }
+
+  return site_instance_for_third_party_subframes_;
+}
+
 void BrowsingInstance::RegisterSiteInstance(SiteInstance* site_instance) {
   DCHECK(static_cast<SiteInstanceImpl*>(site_instance)
              ->browsing_instance_.get() ==
          this);
   DCHECK(static_cast<SiteInstanceImpl*>(site_instance)->HasSite());
   std::string site = site_instance->GetSiteURL().possibly_invalid_spec();
 
   // Only register if we don't have a SiteInstance for this site already.
   // It's possible to have two SiteInstances point to the same site if two
   // tabs are navigated there at the same time.  (We don't call SetSite or
@@ skipping 14 matching lines @@
   std::string site = site_instance->GetSiteURL().possibly_invalid_spec();
 
   // Only unregister the SiteInstance if it is the same one that is registered
   // for the site.  (It might have been an unregistered SiteInstance.  See the
   // comments in RegisterSiteInstance.)
   SiteInstanceMap::iterator i = site_instance_map_.find(site);
   if (i != site_instance_map_.end() && i->second == site_instance) {
     // Matches, so erase it.
     site_instance_map_.erase(i);
   }
+  if (site_instance_for_third_party_subframes_ == site_instance)
+    site_instance_for_third_party_subframes_ = nullptr;
 }
 
 BrowsingInstance::~BrowsingInstance() {
   // We should only be deleted when all of the SiteInstances that refer to
   // us are gone.
   DCHECK(site_instance_map_.empty());
   DCHECK_EQ(0u, active_contents_count_);
 }
 
 }  // namespace content