Use process-per-app-instance for hosted apps without background permission.

content/browser/content_browser_client.h

Index: content/browser/content_browser_client.h
diff --git a/content/browser/content_browser_client.h b/content/browser/content_browser_client.h
index 84ddae1a056a12df1c630a1a6d4d67e281acbfab..eeba943287927e02c365a47af08de59df38dfe2b 100644
--- a/content/browser/content_browser_client.h
+++ b/content/browser/content_browser_client.h
@@ -86,6 +86,10 @@ class ContentBrowserClient {
   // group different url schemes in the same SiteInstance.
   virtual GURL GetEffectiveURL(Profile* profile, const GURL& url) = 0;
 
+  // Returns whether all instances of the specified URL should be rendered by
+  // the same process, rather than using process-per-site-instance.
+  virtual bool ShouldUseProcessPerSite(Profile* profile, const GURL& url) = 0;
+
   // Returns whether a specified URL is to be considered the same as any
   // SiteInstance.
   virtual bool IsURLSameAsAnySiteInstance(const GURL& url) = 0;