[NoStatePrefetch] Track redirects in UMA

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 47ad9e50e375a7ea7ac01645aa5589c34cf14ad9..204c30f62b784cfe90f25c3259a0d30c1ee07df5 100644
--- a/chrome/browser/prerender/prerender_manager.h
+++ b/chrome/browser/prerender/prerender_manager.h
@@ -199,11 +199,19 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
       double fraction_plt_elapsed_at_swap_in,
       const GURL& url);
 
-  // Called when a resource has been loaded by NoStatePrefetch.
+  // Called when a NoStatePrefetch request has received a response (including
+  // redirects). May be called several times per resource, in case of redirects.
   void RecordResourcePrefetch(Origin origin,
                               bool is_main_resource,
+                              bool is_redirect,
                               bool is_no_store);
 
+  // Called when a NoStatePrefetch resource has been loaded. This is called only
+  // once per resource, when all redirects have been resolved.
+  void RecordPrefetchRedirectCount(Origin origin,
+                                   bool is_main_resource,
+                                   size_t redirect_count);
+
   static PrerenderManagerMode GetMode();
   static void SetMode(PrerenderManagerMode mode);
   static bool IsPrerenderingPossible();