[NoStatePrefetch] Cancel repeated prefetches with FINAL_STATUS_DUPLICATE

chrome/browser/prerender/prerender_manager.cc

Index: chrome/browser/prerender/prerender_manager.cc
diff --git a/chrome/browser/prerender/prerender_manager.cc b/chrome/browser/prerender/prerender_manager.cc
index 2fdd033fc5c407ea5416ad4daf5fbe06bf9d2fe2..e46500eab03d3f62ab5fccf61f6af675732092be 100644
--- a/chrome/browser/prerender/prerender_manager.cc
+++ b/chrome/browser/prerender/prerender_manager.cc
@@ -575,6 +575,7 @@ void PrerenderManager::RecordNoStateFirstContentfulPaint(const GURL& url,
   base::TimeDelta prefetch_age;
   Origin origin;
   GetPrefetchInformation(url, &prefetch_age, &origin);
+  OnPrefetchUsed(url);
 
   histograms_->RecordPrefetchFirstContentfulPaintTime(
       origin, is_no_store, was_hidden, time, prefetch_age);
@@ -601,6 +602,7 @@ void PrerenderManager::RecordPrerenderFirstContentfulPaint(
   // histogram recording, below.
   Origin unused_origin;
   GetPrefetchInformation(url, &prefetch_age, &unused_origin);
+  OnPrefetchUsed(url);
 
   base::TimeTicks swap_ticks = tab_helper->swap_ticks();
   bool fcp_recorded = false;
@@ -939,8 +941,17 @@ std::unique_ptr<PrerenderHandle> PrerenderManager::AddPrerender(
     return nullptr;
   }
 
-  if (PrerenderData* preexisting_prerender_data =
-          FindPrerenderData(url, session_storage_namespace)) {
+  if (IsNoStatePrefetch(origin)) {
+    base::TimeDelta prefetch_age;
+    Origin origin;

[pasko, 2017/01/04 15:00:45]

overriding |origin| in this local scope looks dangerous, can it be
|prefetch_origin|?

+    GetPrefetchInformation(url, &prefetch_age, &origin);
+    if (!prefetch_age.is_zero() && prefetch_age < config_.time_to_live) {
+      RecordFinalStatusWithoutCreatingPrerenderContents(url, origin,

[pasko, 2017/01/04 15:00:45]

this should register the origin from the AddPrerender arg, not the origin from
prefetch information, right?

[droger, 2017/01/04 15:14:48]

This is a bug, good catch.
The local variable should not be used, only the parameter from the function is
important.

+                                                        FINAL_STATUS_DUPLICATE);
+      return nullptr;
+    }
+  } else if (PrerenderData* preexisting_prerender_data =
+                 FindPrerenderData(url, session_storage_namespace)) {
     RecordFinalStatusWithoutCreatingPrerenderContents(
         url, origin, FINAL_STATUS_DUPLICATE);
     return base::WrapUnique(new PrerenderHandle(preexisting_prerender_data));
@@ -1204,7 +1215,9 @@ void PrerenderManager::GetPrefetchInformation(const GURL& url,
       break;
     }
   }
+}
 
+void PrerenderManager::OnPrefetchUsed(const GURL& url) {
   // Loading a prefetched URL resets the revalidation bypass. Remove all
   // matching urls from the prefetch list for more accurate metrics.
   prefetches_.erase(