Top document isolation mode prototype

content/browser/browsing_instance.cc

Index: content/browser/browsing_instance.cc
diff --git a/content/browser/browsing_instance.cc b/content/browser/browsing_instance.cc
index 1d5f8953769f92efbc770b3ca88331235d4d8002..d76de7e638263514cb2b2e64f4681aafdd82598d 100644
--- a/content/browser/browsing_instance.cc
+++ b/content/browser/browsing_instance.cc
@@ -36,15 +36,37 @@ SiteInstance* BrowsingInstance::GetSiteInstanceForURL(const GURL& url) {
   if (i != site_instance_map_.end())
     return i->second;
 
+  bool use_doghouse = !site_instance_map_.empty() &&
+                      base::CommandLine::ForCurrentProcess()->HasSwitch(
+                          switches::kDogHouseProcess);
+
+  if (use_doghouse) {
+    if (SiteInstance* doghouse = GetDoghouseSiteInstance()) {
+      return doghouse;
+    }
+  }
+
 
   // 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);
+
+  // TODO(xiaochengh): Say something here...
+  instance->SetForDoghouse(use_doghouse);

[ncarter (slow), 2016/03/14 17:42:24]

I think this choice (of which SiteInstance becomes the doghouse) needs to
somehow be aware of main frame / subframe state, which simply isn't available at
this level.

My expectation is that the first SiteInstance we create will be for the main
frame, which we want to be non-doghouse process.

The crashes you see may be process kills due to the LockToOrigin checks.
Basically, you cannot have UseDedicatedProcessesForAllSites() return true and
then also put two different sites in the same renderer process: the process will
be locked only to the first origin, and we will kill the renderer when the
second site tries to e.g. read document.cookie.

The solution is to not have UseDedicatedProcessesForAllSites() return true in
doghouse mode. Ultimately doghouse is going to be a fourth site isolation mode
(after --site-per-process, --isolate-extensions, and
--isolate-sites-for-testing). Getting this mode implemented right seems like
something that will require a pretty deep knowledge of the process model, so I'm
happy to take it on -- I actually started hacking on it on Friday. I am
optimistic that I can have a patch up today.

   return instance;
 }
 
+SiteInstance* BrowsingInstance::GetDoghouseSiteInstance() const {
+  for (SiteInstanceMap::const_iterator i = site_instance_map_.begin();
+       i != site_instance_map_.end(); ++i) {
+    if (i->second->IsForDoghouse())
+      return i->second;
+  }
+  return nullptr;
+}
+
 void BrowsingInstance::RegisterSiteInstance(SiteInstance* site_instance) {
   DCHECK(static_cast<SiteInstanceImpl*>(site_instance)
              ->browsing_instance_.get() ==