android: Add a method to let Java know whether a prerender has finished loading.

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 174 matching lines @@
   static bool IsNoUseGroup();
 
   // Query the list of current prerender pages to see if the given web contents
   // is prerendering a page. The optional parameter |origin| is an output
   // parameter which, if a prerender is found, is set to the Origin of the
   // prerender |web_contents|.
   bool IsWebContentsPrerendering(const content::WebContents* web_contents,
                                  Origin* origin) const;
 
   // Whether the PrerenderManager has an active prerender with the given url and
-  // SessionStorageNamespace associated with the given WebContens.
+  // SessionStorageNamespace associated with the given WebContents.

[gavinp, 2016/02/25 18:44:55]

Thanks. This has bugged me for a while, but never had a change close enough.

   bool HasPrerenderedUrl(GURL url, content::WebContents* web_contents) const;
 
+  // Whether the PrerenderManager has an active prerender with the given url and
+  // SessionStorageNamespace associated with the given WebContents, and that
+  // prerender has finished loading..
+  bool HasPrerenderedAndFinishedLoadingUrl(
+      GURL url,
+      content::WebContents* web_contents) const;
+
   // Returns the PrerenderContents object for the given web_contents, otherwise
   // returns NULL. Note that the PrerenderContents may have been Destroy()ed,
   // but not yet deleted.
   PrerenderContents* GetPrerenderContents(
       const content::WebContents* web_contents) const;
 
   // Returns the PrerenderContents object for a given child_id, route_id pair,
   // otherwise returns NULL. Note that the PrerenderContents may have been
   // Destroy()ed, but not yet deleted.
   virtual PrerenderContents* GetPrerenderContentsForRoute(
@@ skipping 333 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_