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

chrome/browser/prerender/prerender_resource_handler_unittest.cc

Index: chrome/browser/prerender/prerender_resource_handler_unittest.cc
diff --git a/chrome/browser/prerender/prerender_resource_handler_unittest.cc b/chrome/browser/prerender/prerender_resource_handler_unittest.cc
index f6501d890214948abbc7a9a8fe1184f4c91c6fb4..566adf55d4593af82bdfdb073db72b66a0a457be 100644
--- a/chrome/browser/prerender/prerender_resource_handler_unittest.cc
+++ b/chrome/browser/prerender/prerender_resource_handler_unittest.cc
@@ -110,8 +110,9 @@ class PrerenderResourceHandlerTest : public testing::Test {
     loop_.RunAllPending();
   }
 
-  void SetLastHandledURL(const GURL& url, const std::vector<GURL>& alias_urls,
-                         const GURL& referrer) {
+  void SetLastHandledURL(std::pair<int, int> child_route_id_pair,
+                         const GURL& url, const std::vector<GURL>& alias_urls,
+                         const GURL& referrer, bool make_pending) {
     last_handled_url_ = url;
     alias_urls_ = alias_urls;
     referrer_ = referrer;