[wip] Introduce SiteInstanceKeepAlive.

content/browser/site_instance_impl.h

Index: content/browser/site_instance_impl.h
diff --git a/content/browser/site_instance_impl.h b/content/browser/site_instance_impl.h
index edaeb3e702d75910effe7b4064ba20a3396ad84e..8377f539ae841f35af242fa9b42228cb6b8bce64 100644
--- a/content/browser/site_instance_impl.h
+++ b/content/browser/site_instance_impl.h
@@ -13,6 +13,7 @@
 
 namespace content {
 class RenderProcessHostFactory;
+class SiteInstanceKeepAlive;
 
 class CONTENT_EXPORT SiteInstanceImpl : public SiteInstance,
                                         public RenderProcessHostObserver {
@@ -26,6 +27,8 @@ class CONTENT_EXPORT SiteInstanceImpl : public SiteInstance,
   virtual bool IsRelatedSiteInstance(const SiteInstance* instance) OVERRIDE;
   virtual BrowserContext* GetBrowserContext() const OVERRIDE;
 
+  scoped_ptr<SiteInstanceKeepAlive> AcquireKeepAlive();
+
   // 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
@@ -124,6 +127,17 @@ class CONTENT_EXPORT SiteInstanceImpl : public SiteInstance,
   DISALLOW_COPY_AND_ASSIGN(SiteInstanceImpl);
 };
 
+class CONTENT_EXPORT SiteInstanceKeepAlive {
+ public:
+  explicit SiteInstanceKeepAlive(scoped_refptr<SiteInstanceImpl> instance);

[mfomitchev, 2014/02/14 16:21:36]

Perhaps we should make this constructor non-puiblic and force clients to use
AcquireKeepAlive() instead?

+  ~SiteInstanceKeepAlive();
+
+ private:
+  scoped_refptr<SiteInstanceImpl> instance_;
+
+  DISALLOW_COPY_AND_ASSIGN(SiteInstanceKeepAlive);
+};
+
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_SITE_INSTANCE_IMPL_H_