Add pending preloads indexed by routing id. Start preloading once we navigate.

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 64adb11ce0e8569e371e3ba572f58775666a6d79..22469987a14aeb9b538d6e623d62ddbfe0d1b1f5 100644
--- a/chrome/browser/prerender/prerender_manager.h
+++ b/chrome/browser/prerender/prerender_manager.h
@@ -7,6 +7,7 @@
 #pragma once
 
 #include <list>
+#include <map>
 #include <vector>
 
 #include "base/ref_counted.h"
@@ -44,6 +45,10 @@ class PrerenderManager : public base::RefCounted<PrerenderManager> {
   bool AddPreload(const GURL& url, const std::vector<GURL>& alias_urls,
                   const GURL& referrer);
 
+  void AddPendingPreload(int route_id, const GURL& url,
+                         const std::vector<GURL>& alias_urls,
+                         const GURL& referrer);
+
   // For a given TabContents that wants to navigate to the URL supplied,
   // determines whether a preloaded version of the URL can be used,
   // and substitutes the prerendered RVH into the TabContents.  Returns
@@ -116,6 +121,10 @@ class PrerenderManager : public base::RefCounted<PrerenderManager> {
 
   static void RecordPrefetchTagObservedOnUIThread();
 
+  // Called when removing a preload to ensure we clean up any pending preloads
+  // that might remain in the map.
+  void RemovePendingPreload(PrerenderContents* entry);
+
   Profile* profile_;
 
   base::TimeDelta max_prerender_age_;
@@ -124,6 +133,19 @@ class PrerenderManager : public base::RefCounted<PrerenderManager> {
   // List of prerendered elements.
   std::list<PrerenderContentsData> prerender_list_;
 
+  struct PendingContentsData {
+    PendingContentsData(const GURL& url, const std::vector<GURL>& alias_urls,
+                        const GURL& referrer)
+        : url_(url), alias_urls_(alias_urls), referrer_(referrer) {
+    }
+    ~PendingContentsData() {}
+    const GURL url_;
+    const std::vector<GURL> alias_urls_;
+    const GURL referrer_;
+  };
+
+  std::map<int, PendingContentsData> pending_prerender_map_;
+
   // Default maximum permitted elements to prerender.
   static const unsigned int kDefaultMaxPrerenderElements = 1;