Implement PrerenderManager::AddPrerenderForOffline()

chrome/browser/prerender/prerender_manager.h

Index: chrome/browser/prerender/prerender_manager.h
diff --git a/chrome/browser/prerender/prerender_manager.h b/chrome/browser/prerender/prerender_manager.h
index 692d971df9b23ad5e3d1633115bf175237054b14..d64fc202f41b789a4e6d7a764e3445c32a313363 100644
--- a/chrome/browser/prerender/prerender_manager.h
+++ b/chrome/browser/prerender/prerender_manager.h
@@ -151,6 +151,22 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
       content::SessionStorageNamespace* session_storage_namespace,
       const gfx::Size& size);
 
+  // Adds a prerender for the background loader. Returns a caller-owned
+  // PrerenderHandle* if the URL was added, NULL if it was not.
+  //
+  // The caller may set an observer on the handle to receive load events. When
+  // the caller is done using the WebContents, it should call OnCancel() on the
+  // handle to free the resources associated with the prerender.
+  //
+  // The caller must provide two guarantees:
+  // 1. It must never ask for a swap-in;
+  // 2. The SessionStorageNamespace must not be shared with any tab / page load
+  //    to avoid swapping in from there.
+  PrerenderHandle* AddPrerenderForOffline(
+      const GURL& url,
+      content::SessionStorageNamespace* session_storage_namespace,
+      const gfx::Size& size);
+
   // Cancels all active prerenders.
   void CancelAllPrerenders();