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

chrome/browser/prerender/prerender_manager.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/prerender/prerender_manager.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 272 matching lines @@
   for (std::list<PrerenderContentsData>::const_iterator it =
            prerender_list_.begin();
        it != prerender_list_.end();
        ++it) {
     if (it->contents_->IsPendingEntry(url))
       return true;
   }
   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),
       profile_(profile),
       prerender_tracker_(prerender_tracker),
       prerender_contents_factory_(PrerenderContents::CreateFactory()),
       last_prerender_start_time_(GetCurrentTimeTicks() -
           base::TimeDelta::FromMilliseconds(kMinTimeBetweenPrerendersMs)),
       weak_factory_(this),
       prerender_history_(new PrerenderHistory(kHistoryLength)),
@@ skipping 186 matching lines @@
 
 void PrerenderManager::CancelAllPrerenders() {
   DCHECK(CalledOnValidThread());
   while (!prerender_list_.empty()) {
     PrerenderContentsData data = prerender_list_.front();
     DCHECK(data.contents_);
     data.contents_->Destroy(FINAL_STATUS_CANCELLED);
   }
 }
 
+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()) {
     PrerenderContentsData data = prerender_list_.front();
     if (IsPrerenderElementFresh(data.start_time_))
       return;
     data.contents_->Destroy(FINAL_STATUS_TIMED_OUT);
   }
   MaybeStopSchedulingPeriodicCleanups();
 }
@@ skipping 607 matching lines @@
   if (!render_process_host || !render_process_host->GetBrowserContext())
     return NULL;
   Profile* profile = Profile::FromBrowserContext(
       render_process_host->GetBrowserContext());
   if (!profile)
     return NULL;
   return PrerenderManagerFactory::GetInstance()->GetForProfile(profile);
 }
 
 }  // namespace prerender