Implement PrerenderManager::AddPrerenderForOffline()

chrome/browser/prerender/prerender_manager.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 CHROME_BROWSER_PRERENDER_PRERENDER_MANAGER_H_
 #define CHROME_BROWSER_PRERENDER_PRERENDER_MANAGER_H_
 
 #include <stdint.h>
 
 #include <list>
@@ skipping 133 matching lines @@
 
   // Adds a prerender for Instant Search |url| if valid. The
   // |session_storage_namespace| matches the namespace of the active tab at the
   // time the prerender is generated. Returns a caller-owned PrerenderHandle* or
   // NULL.
   PrerenderHandle* AddPrerenderForInstant(
       const GURL& url,
       content::SessionStorageNamespace* session_storage_namespace,
       const gfx::Size& size);
 
+  // Adds a prerender from an external request that will always prerender.

[pasko, 2016/04/05 11:49:56]

This is not an "external request", calling it such is confusing (or maybe I
misunderstand the terminology).

Please add the comment from the doc as we discussed, some obvious stuff can be
stripped. My suggestion:

// 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 to as for a swap-in;
// 2. The SessionStorageNamespace must not be shared with any tab / page load
//    to avoid swapping in from there.

[gabadie, 2016/04/05 13:35:24]

My bad. Done.

+  PrerenderHandle* AddPrerenderForOffline(
+      const GURL& url,
+      content::SessionStorageNamespace* session_storage_namespace,
+      const gfx::Size& size);
+
   // Cancels all active prerenders.
   void CancelAllPrerenders();
 
   // If |url| matches a valid prerendered page and |params| are compatible, try
   // to swap it and merge browsing histories. Returns |true| and updates
   // |params->target_contents| if a prerendered page is swapped in, |false|
   // otherwise.
   bool MaybeUsePrerenderedPage(const GURL& url,
                                chrome::NavigateParams* params);
 
@@ skipping 397 matching lines @@
   // Set of process hosts being prerendered.
   typedef std::set<content::RenderProcessHost*> PrerenderProcessSet;
   PrerenderProcessSet prerender_process_hosts_;
 
   DISALLOW_COPY_AND_ASSIGN(PrerenderManager);
 };
 
 }  // namespace prerender
 
 #endif  // CHROME_BROWSER_PRERENDER_PRERENDER_MANAGER_H_