Inside of content, prefer SiteInstanceImpl to SiteInstance.

content/browser/site_instance_impl.cc

Index: content/browser/site_instance_impl.cc
diff --git a/content/browser/site_instance_impl.cc b/content/browser/site_instance_impl.cc
index 40271d4354f0dae21b17a6c48e53a5a1012bbde9..9045a7a9f390d996cd8c478cc8373b7f5a08ea25 100644
--- a/content/browser/site_instance_impl.cc
+++ b/content/browser/site_instance_impl.cc
@@ -194,7 +194,7 @@ bool SiteInstanceImpl::HasRelatedSiteInstance(const GURL& url) {
 
 scoped_refptr<SiteInstance> SiteInstanceImpl::GetRelatedSiteInstance(
     const GURL& url) {
-  return browsing_instance_->GetSiteInstanceForURL(url);
+  return GetRelatedSiteInstanceImpl(url);
 }
 
 bool SiteInstanceImpl::IsRelatedSiteInstance(const SiteInstance* instance) {
@@ -227,6 +227,11 @@ bool SiteInstanceImpl::HasWrongProcessForURL(const GURL& url) {
       GetProcess(), browsing_instance_->browser_context(), site_url);
 }
 
+scoped_refptr<SiteInstanceImpl> SiteInstanceImpl::GetRelatedSiteInstanceImpl(
+    const GURL& url) {
+  return browsing_instance_->GetSiteInstanceForURL(url);
+}
+
 scoped_refptr<SiteInstanceImpl>
 SiteInstanceImpl::GetDefaultSubframeSiteInstance() {
   return browsing_instance_->GetDefaultSubframeSiteInstance();