Inside of content, prefer SiteInstanceImpl to SiteInstance.

content/browser/site_instance_impl.h

 // 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.
 
 #ifndef CONTENT_BROWSER_SITE_INSTANCE_IMPL_H_
 #define CONTENT_BROWSER_SITE_INSTANCE_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 32 matching lines @@
   int32_t GetId() override;
   bool HasProcess() const override;
   RenderProcessHost* GetProcess() override;
   BrowserContext* GetBrowserContext() const override;
   const GURL& GetSiteURL() const override;
   scoped_refptr<SiteInstance> GetRelatedSiteInstance(const GURL& url) override;
   bool IsRelatedSiteInstance(const SiteInstance* instance) override;
   size_t GetRelatedActiveContentsCount() override;
   bool RequiresDedicatedProcess() override;
 
+  // Same as GetRelatedSiteInstance, but returns a SiteInstanceImpl.
+  scoped_refptr<SiteInstanceImpl> GetRelatedSiteInstanceImpl(const GURL& url);
+
   // Returns the SiteInstance, related to this one, that should be used
   // for subframes when an oopif is required, but a dedicated process is not.
   // This SiteInstance will be created if it doesn't already exist. There is
   // at most one of these per BrowsingInstance.
   scoped_refptr<SiteInstanceImpl> GetDefaultSubframeSiteInstance();
 
   // Set the web site that this SiteInstance is rendering pages for.
   // This includes the scheme and registered domain, but not the port.  If the
   // URL does not have a valid registered domain, then the full hostname is
   // stored.
@@ skipping 123 matching lines @@
   bool is_default_subframe_site_instance_;
 
   base::ObserverList<Observer, true> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(SiteInstanceImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_SITE_INSTANCE_IMPL_H_