"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::GetDefaultSubframeSiteInstance() {

[Charlie Reis, 2016/03/25 19:47:12]

Can we put a CHECK(IsTopDocumentIsolationEnabled()) here?  Or at least
AreCrossProcessFramesPossible()?  Just want to make sure we don't call it in
default Chrome.

[ncarter (slow), 2016/03/28 22:00:28]

I made this the stricter variant, CHECK(IsTopDocumentIsolationEnabled()). It's
still not 100% clear how SiteInstance coalescing will work in the extension(a,b)
case, and whether that will use the default subframe siteinstance or not, so
let's restrict it to --top-document-isolation for now, and relax this constraint
as we make progress.

[Charlie Reis, 2016/03/29 17:17:12]

Acknowledged.

+  if (!default_subframe_site_instance_) {
+    SiteInstanceImpl* instance = new SiteInstanceImpl(this);
+    instance->set_is_default_subframe_site_instance();
+    // TODO(nick): This is a hack for now.
+    instance->SetSite(GURL("http://web-subframes.invalid"));

[Charlie Reis, 2016/03/25 19:47:12]

Yeah, we can chat about what to put here long term (or how to avoid it).

[ncarter (slow), 2016/03/28 22:00:28]

If we rip this out now, the PopupAndRedirection test sees a pretty big behavior
change. I think that's a sign of us falling back to the SiteURL somewhere we
shouldn't be, but for now I think it's safest to use a sentinel value here.

Open to other suggestions here -- let me know if you have ideas.

+    default_subframe_site_instance_ = instance;
+  }
+
+  return default_subframe_site_instance_;
+}
+
 void BrowsingInstance::RegisterSiteInstance(SiteInstance* site_instance) {
   DCHECK(static_cast<SiteInstanceImpl*>(site_instance)
              ->browsing_instance_.get() ==
          this);
   DCHECK(static_cast<SiteInstanceImpl*>(site_instance)->HasSite());
+
+  // Don't register the default subframe SiteInstance, to prevent it from being
+  // returned by GetSiteInstanceForURL.
+  if (default_subframe_site_instance_ == site_instance)
+    return;
+
   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
   // register them until DidNavigate.)  If there is a previously existing
   // SiteInstance for this site, we just won't register the new one.
   SiteInstanceMap::iterator i = site_instance_map_.find(site);
   if (i == site_instance_map_.end()) {
     // Not previously registered, so register it.
     site_instance_map_[site] = site_instance;
   }
 }
 
 void BrowsingInstance::UnregisterSiteInstance(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 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 (default_subframe_site_instance_ == site_instance)
+    default_subframe_site_instance_ = 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