"Top Document Isolation" mode

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..69799a5c38374e305827f8d9db0d0c770f185994 100644
--- a/content/browser/browsing_instance.cc
+++ b/content/browser/browsing_instance.cc
@@ -7,6 +7,7 @@
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "content/browser/site_instance_impl.h"
+#include "content/common/site_isolation_policy.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/content_browser_client.h"
 #include "content/public/common/content_switches.h"
@@ -36,7 +37,6 @@ SiteInstance* BrowsingInstance::GetSiteInstanceForURL(const GURL& url) {
   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);
 
@@ -45,11 +45,31 @@ SiteInstance* BrowsingInstance::GetSiteInstanceForURL(const GURL& url) {
   return instance;
 }
 
+SiteInstance* BrowsingInstance::GetDefaultSubframeSiteInstance() {
+  // This should only be used for --top-document-isolation mode.
+  CHECK(SiteIsolationPolicy::IsTopDocumentIsolationEnabled());
+  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"));
+    default_subframe_site_instance_ = instance;
+  }
+
+  return default_subframe_site_instance_;
+}
+
 void BrowsingInstance::RegisterSiteInstance(SiteInstance* site_instance) {
   DCHECK(static_cast<SiteInstanceImpl*>(site_instance)

[dcheng, 2016/03/29 08:09:16]

Unrelated to this CL, but is there a reason RegisterSiteInstance() and
UnregisterSiteInstance() don't just take a SiteInstanceImpl? It seems weird to
always pass in SiteInstanceImpls as SiteInstance and then downcast back to
SiteInstanceImpl.

[ncarter (slow), 2016/03/29 16:28:33]

Done locally, will upload with other reviewer fixes.

[ncarter (slow), 2016/03/29 23:30:57]

Done.

              ->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.
@@ -79,6 +99,8 @@ void BrowsingInstance::UnregisterSiteInstance(SiteInstance* 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() {