Cancel prerenders from Omnibox if we navigate to a different URL than predicted

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 59bb8609fd6a56cf8b05fb11f920b8a2b014b779..e4ddaf3dcccf03fea10cc9e920c53db55b5a7e1c 100644
--- a/chrome/browser/prerender/prerender_manager.cc
+++ b/chrome/browser/prerender/prerender_manager.cc
@@ -290,6 +290,11 @@ bool PrerenderManager::IsPendingEntry(const GURL& url) const {
   return false;
 }
 
+bool PrerenderManager::IsPrerendering(const GURL& url) {

[Peter Kasting, 2012/01/21 00:22:52]

Nit: Can you make this file's definition order match the declaration order?  I
notice this was declared after CancelOmniboxPrerenders() in the header but here
appears above it.

[dominich, 2012/01/23 22:50:07]

Done.

+  DCHECK(CalledOnValidThread());
+  return (FindEntry(url) != NULL);
+}
+
 PrerenderManager::PrerenderManager(Profile* profile,
                                    PrerenderTracker* prerender_tracker)
     : enabled_(true),
@@ -496,6 +501,26 @@ void PrerenderManager::CancelAllPrerenders() {
   }
 }
 
+void PrerenderManager::CancelOmniboxPrerenders() {
+  DCHECK(CalledOnValidThread());
+  // Calling Destroy will invalidate iterators as it erases the entry from
+  // |prerender_list_| so we must first gather those contents to destroy and
+  // then destroy them.

[Peter Kasting, 2012/01/21 00:22:52]

Nit: Our normal practice for this would be to do one of the following:

for (it = list.begin(); it != list.end(); ) {
  // OPTION 1
  if (should_destroy(it))
    it = it->Destroy();  // Requires that Destroy() ultimately return the result
of list.erase()
  else
    ++it;

  // OR, OPTION 2
  cur = it++;
  if (should_destroy(cur))
    cur->Destroy();
}

These have the advantage of being somewhat shorter and cheaper in addition to
being more common.

[dominich, 2012/01/23 22:50:07]

Done.

+  std::vector<PrerenderContents*> destroy_contents;
+  for (std::list<PrerenderContentsData>::iterator it = prerender_list_.begin();
+       it != prerender_list_.end();
+       ++it) {
+    if (it->contents_->origin() == ORIGIN_OMNIBOX)
+      destroy_contents.push_back(it->contents_);
+  }
+
+  for (std::vector<PrerenderContents*>::iterator it = destroy_contents.begin();
+       it != destroy_contents.end();
+       ++it) {
+    (*it)->Destroy(FINAL_STATUS_CANCELLED);
+  }
+}
+
 void PrerenderManager::DeleteOldEntries() {
   DCHECK(CalledOnValidThread());
   while (!prerender_list_.empty()) {