Handle interface to prerenders.

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 <algorithm>
+#include <functional>
 #include <set>
 #include <string>

[mmenke, 2012/07/09 18:06:57]

While you're here, set doesn't look to be used in this file, and string is
included in the header file.

[gavinp, 2012/07/11 17:04:00]

Done.

 #include <vector>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/logging.h"
 #include "base/memory/weak_ptr.h"
 #include "base/metrics/histogram.h"
 #include "base/stl_util.h"
 #include "base/time.h"
 #include "base/utf_string_conversions.h"
@@ skipping 80 matching lines @@
 // This ensures that there is no bias in terms of the page load times
 // of the pages forming the difference between the two sets.
 
 bool NeedMatchCompleteDummyForFinalStatus(FinalStatus final_status) {
   return final_status != FINAL_STATUS_USED &&
       final_status != FINAL_STATUS_TIMED_OUT &&
       final_status != FINAL_STATUS_EVICTED &&
       final_status != FINAL_STATUS_MANAGER_SHUTDOWN &&
       final_status != FINAL_STATUS_APP_TERMINATING &&
       final_status != FINAL_STATUS_WINDOW_OPENER &&
-      final_status != FINAL_STATUS_FRAGMENT_MISMATCH &&
       final_status != FINAL_STATUS_CACHE_OR_HISTORY_CLEARED &&
       final_status != FINAL_STATUS_CANCELLED &&
-      final_status != FINAL_STATUS_SESSION_STORAGE_NAMESPACE_MISMATCH &&
       final_status != FINAL_STATUS_DEVTOOLS_ATTACHED &&
       final_status != FINAL_STATUS_CROSS_SITE_NAVIGATION_PENDING;
 }
 
 }  // namespace
 
 class PrerenderManager::OnCloseTabContentsDeleter
     : public content::WebContentsDelegate,
       public base::SupportsWeakPtr<
           PrerenderManager::OnCloseTabContentsDeleter> {
@@ skipping 41 matching lines @@
 // static
 bool PrerenderManager::is_prefetch_enabled_ = false;
 
 // static
 int PrerenderManager::prerenders_per_session_count_ = 0;
 
 // static
 PrerenderManager::PrerenderManagerMode PrerenderManager::mode_ =
     PRERENDER_MODE_ENABLED;
 
-struct PrerenderManager::PrerenderContentsData {
-  PrerenderContents* contents_;
-  base::Time start_time_;
-  int active_count_;
-  PrerenderContentsData(PrerenderContents* contents, base::Time start_time)
-      : contents_(contents),
-        start_time_(start_time),
-        active_count_(1) {
-    CHECK(contents);
-  }
-};
-
 struct PrerenderManager::NavigationRecord {
   GURL url_;
   base::TimeTicks time_;
   NavigationRecord(const GURL& url, base::TimeTicks time)
       : url_(url),
         time_(time) {
   }
 };
 
 PrerenderManager::PrerenderManager(Profile* profile,
@@ skipping 14 matching lines @@
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 }
 
 PrerenderManager::~PrerenderManager() {
 }
 
 void PrerenderManager::Shutdown() {
   DoShutdown();
 }
 
-bool PrerenderManager::AddPrerenderFromLinkRelPrerender(
+PrerenderHandle* PrerenderManager::AddPrerenderFromLinkRelPrerender(
     int process_id,
     int route_id,
     const GURL& url,
     const content::Referrer& referrer,
     gfx::Size size) {
 #if defined(OS_ANDROID)
   // TODO(jcivelli): http://crbug.com/113322 We should have an option to disable
   //                link-prerender and enable omnibox-prerender only.
   return false;
 #else
-  std::pair<int, int> child_route_id_pair(process_id, route_id);
-  PrerenderContentsDataList::iterator it =
-      FindPrerenderContentsForChildRouteIdPair(child_route_id_pair);
-  if (it != prerender_list_.end()) {
+  if (PrerenderHandle::PrerenderData* parent_prerender_data =
+          FindPrerenderDataForChildAndRoute(process_id, route_id)) {
     // Instead of prerendering from inside of a running prerender, we will defer
     // this request until its launcher is made visible.
-    it->contents_->AddPendingPrerender(url, referrer, size);
-    return true;
+    if (PrerenderContents* contents = parent_prerender_data->contents) {
+      pending_prerender_list_.push_back(PrerenderHandle::PrerenderData(this));
+      PrerenderHandle* prerender_handle = CreatePrerenderHandleForPrerenderData(
+          &pending_prerender_list_.back());
+      contents->AddPendingPrerender(
+          prerender_handle->weak_ptr_factory_.GetWeakPtr(),
+          url, referrer, size);
+      return prerender_handle;
+    }
   }
 
   // Unit tests pass in a process_id == -1.
   SessionStorageNamespace* session_storage_namespace = NULL;
   if (process_id != -1) {
     RenderViewHost* source_render_view_host =
         RenderViewHost::FromID(process_id, route_id);
     if (!source_render_view_host || !source_render_view_host->GetView())
-      return false;
+      return NULL;
     session_storage_namespace =
         source_render_view_host->GetSessionStorageNamespace();
 
     if (size.IsEmpty()) {

[dominich, 2012/07/11 17:50:45]

who's doing this check now? if size should never be empty, please CHECK as such.
This was added by a recent jam change, iirc. check why he did it before
removing.

[gavinp, 2012/07/11 18:17:13]

The size is added at PrerendererClient::willAddPrender(), and the only way the
program counter would ever have entered this test was if RenderView::GetSize()
was empty. And would we then, after having empty bounds on a WebView, expect the
WebContentsView to have a non-empty container bounds? This code should have been
removed from PrerenderContents in http://codereview.chromium.org/10244007/ , as
part of the cleanup when making the new API, and it's to my shame that I didn't
do that.

We can DCHECK it's not empty. I'll add that, and fix the unit tests so they
don't send in empty sizes, too.

       // Use the size of the tab requesting the prerendering.
       WebContents* web_contents =
           WebContents::FromRenderViewHost(source_render_view_host);
       if (web_contents && web_contents->GetView()) {
         gfx::Rect container_bounds;
         web_contents->GetView()->GetContainerBounds(&container_bounds);
         size = container_bounds.size();
       }
     }
   }
 
   return AddPrerender(ORIGIN_LINK_REL_PRERENDER,
                       process_id, url, referrer, size,
                       session_storage_namespace);
 #endif
 }
 
-bool PrerenderManager::AddPrerenderFromOmnibox(
+PrerenderHandle* PrerenderManager::AddPrerenderFromOmnibox(
     const GURL& url,
     SessionStorageNamespace* session_storage_namespace,
     gfx::Size size) {
   if (!IsOmniboxEnabled(profile_))
-    return false;
-  return AddPrerender(ORIGIN_OMNIBOX, -1, url,
-                      content::Referrer(), size,
+    return NULL;
+  return AddPrerender(ORIGIN_OMNIBOX, -1, url, content::Referrer(), size,
                       session_storage_namespace);
 }
 
-void PrerenderManager::MaybeCancelPrerender(const GURL& url) {
-  PrerenderContentsDataList::iterator it = FindPrerenderContentsForURL(url);
-  if (it == prerender_list_.end())
-    return;
-  PrerenderContentsData& prerender_contents_data = *it;
-  if (--prerender_contents_data.active_count_ == 0)
-    prerender_contents_data.contents_->Destroy(FINAL_STATUS_CANCELLED);
+void PrerenderManager::StartPendingPrerender(
+    PrerenderHandle* existing_prerender_handle,
+    Origin origin,
+    int process_id,
+    const GURL& url,
+    const content::Referrer& referrer,
+    const gfx::Size& size,
+    content::SessionStorageNamespace* session_storage_namespace) {
+  DCHECK(existing_prerender_handle);
+  DCHECK(existing_prerender_handle->IsValid());
+  DCHECK(existing_prerender_handle->IsPending());
+
+  DCHECK(process_id == -1 || session_storage_namespace);
+
+  scoped_ptr<PrerenderHandle>
+      new_prerender_handle(AddPrerender(origin, process_id, url, referrer,
+                                        size, session_storage_namespace));

[mmenke, 2012/07/10 18:01:13]

IMPORTANT:  AddPerender() can return NULL.  Neither this function nor
SwapPrerenderDataWith() has a NULL check.  Fix that.  Also probably a good idea
to have a unit test for it.

[mmenke, 2012/07/10 18:01:13]

While this code is pretty straight forward, think this line is worthy of a
comment due to its importance.  Maybe something along the lines of "If |url| is
already being prerendered, this will result creating another handle for the
existing PrerenderData.  If it's not being prerendered, this will start a new
prerender (Or return NULL)."

[gavinp, 2012/07/11 17:04:00]

Done. Very good catch, I'm glad you're reviewing this.

+
+  existing_prerender_handle->SwapPrerenderDataWith(new_prerender_handle.get());
+}
+
+void PrerenderManager::DestroyPendingPrerenderData(
+    PrerenderHandle::PrerenderData* pending_prerender_data) {
+  for (std::list<PrerenderHandle::PrerenderData>::iterator
+           it = pending_prerender_list_.begin();
+       it != pending_prerender_list_.end();
+       ++it) {

[mmenke, 2012/07/10 18:01:13]

std::find would be a little simpler.

[gavinp, 2012/07/11 17:04:00]

It would. If only we had address_of().... But we don't. See
http://codereview.chromium.org/10261004/

I don't believe we can use std::find without this function.

Related rant: if we had std::compose(), I could replace about half of my loops
with find and for_each. Alas. I also wouldn't mind nonstd::member_of(). However,
it's probably best for all of us that we don't have these...

[mmenke, 2012/07/11 18:40:05]

Right.  For some reason, I was thinking the list was of PrerenderData*'s rather
than PrerenderData's.

[mmenke, 2012/07/11 18:48:37]

optional:  May actually be a little cleaner to make it a non-copiable class and
use pointers / delete, rather than make it POD.

+    if (&(*it) == pending_prerender_data) {
+      DCHECK_EQ(0, pending_prerender_data->instance_count);
+      InvalidatePrerenderHandlesForPrerenderData(*it);
+      pending_prerender_list_.erase(it);
+      return;
+    }
+  }
+  NOTREACHED();
 }
 
 void PrerenderManager::DestroyPrerenderForRenderView(
     int process_id, int view_id, FinalStatus final_status) {
   DCHECK(CalledOnValidThread());
-  PrerenderContentsDataList::iterator it =
-      FindPrerenderContentsForChildRouteIdPair(
-          std::make_pair(process_id, view_id));
-  if (it != prerender_list_.end()) {
-    PrerenderContents* prerender_contents = it->contents_;
-    prerender_contents->Destroy(final_status);
+  if (PrerenderHandle::PrerenderData* prerender_data =
+          FindPrerenderDataForChildAndRoute(process_id, view_id)) {
+    prerender_data->contents->Destroy(final_status);
   }
 }
 
 void PrerenderManager::CancelAllPrerenders() {
   DCHECK(CalledOnValidThread());
-  while (!prerender_list_.empty()) {
-    PrerenderContentsData data = prerender_list_.front();
-    DCHECK(data.contents_);
-    data.contents_->Destroy(FINAL_STATUS_CANCELLED);
+  while (!active_prerender_list_.empty()) {
+    PrerenderContents* prerender_contents =
+        active_prerender_list_.front().contents;
+    prerender_contents->Destroy(FINAL_STATUS_CANCELLED);
   }
 }
 
 bool PrerenderManager::MaybeUsePrerenderedPage(WebContents* web_contents,
                                                const GURL& url) {
   DCHECK(CalledOnValidThread());
   DCHECK(!IsWebContentsPrerendering(web_contents));
 
-  scoped_ptr<PrerenderContents> prerender_contents(
-      GetEntryButNotSpecifiedWC(url, web_contents));
-  if (prerender_contents.get() == NULL)
+  RenderViewHost* old_render_view_host = web_contents->GetRenderViewHost();
+
+  DeleteOldEntries();
+  DeletePendingDeleteEntries();
+  PrerenderHandle::PrerenderData* prerender_data =
+      FindPrerenderData(url,
+                        old_render_view_host->GetSessionStorageNamespace());
+  if (!prerender_data)
     return false;
+  DCHECK(prerender_data->contents);
+  if (IsNoSwapInExperiment(prerender_data->contents->experiment_id()))
+    return false;
+
+  if (TabContents* new_tab_contents =
+          prerender_data->contents->prerender_contents()) {
+    if (web_contents == new_tab_contents->web_contents())
+      return false;  // Do not swap in to ourself.
+  }
+
+  scoped_ptr<PrerenderContents> prerender_contents(prerender_data->contents);
+  std::list<PrerenderHandle::PrerenderData>::iterator to_erase =
+      FindIteratorForPrerenderContents(prerender_contents.get());
+  DCHECK(active_prerender_list_.end() != to_erase);
+  DCHECK(&(*to_erase) == prerender_data);
+  InvalidatePrerenderHandlesForPrerenderData(*prerender_data);
+  active_prerender_list_.erase(to_erase);
 
   // Do not use the prerendered version if there is an opener object.
   if (web_contents->HasOpener()) {
     prerender_contents.release()->Destroy(FINAL_STATUS_WINDOW_OPENER);
     return false;
   }
 
-  // Even if we match, the location.hash might be different. Record this as a
-  // separate final status.
-  GURL matching_url;
-  bool url_matches = prerender_contents->MatchesURL(url, &matching_url);
-  DCHECK(url_matches);
-  if (url_matches && url.ref() != matching_url.ref()) {
-    prerender_contents.release()->Destroy(FINAL_STATUS_FRAGMENT_MISMATCH);
-    return false;
-  }
-
   // If we are just in the control group (which can be detected by noticing
   // that prerendering hasn't even started yet), record that |web_contents| now
   // would be showing a prerendered contents, but otherwise, don't do anything.
   if (!prerender_contents->prerendering_has_started()) {
     MarkWebContentsAsWouldBePrerendered(web_contents);
     prerender_contents.release()->Destroy(FINAL_STATUS_WOULD_HAVE_BEEN_USED);
     return false;
   }
 
   // Don't use prerendered pages if debugger is attached to the tab.
   // See http://crbug.com/98541
   if (content::DevToolsAgentHostRegistry::IsDebuggerAttached(web_contents)) {
     DestroyAndMarkMatchCompleteAsUsed(prerender_contents.release(),
                                       FINAL_STATUS_DEVTOOLS_ATTACHED);
     return false;
   }
 
   // If the prerendered page is in the middle of a cross-site navigation,
   // don't swap it in because there isn't a good way to merge histories.
   if (prerender_contents->IsCrossSiteNavigationPending()) {
     DestroyAndMarkMatchCompleteAsUsed(
         prerender_contents.release(),
         FINAL_STATUS_CROSS_SITE_NAVIGATION_PENDING);
     return false;
   }
 
-  // If the session storage namespaces don't match, cancel the prerender.
-  RenderViewHost* old_render_view_host = web_contents->GetRenderViewHost();
-  RenderViewHost* new_render_view_host =
-      prerender_contents->prerender_contents()->web_contents()->
-          GetRenderViewHost();
-  DCHECK(old_render_view_host);
-  DCHECK(new_render_view_host);
-  if (old_render_view_host->GetSessionStorageNamespace() !=
-      new_render_view_host->GetSessionStorageNamespace()) {
-    DestroyAndMarkMatchCompleteAsUsed(
-        prerender_contents.release(),
-        FINAL_STATUS_SESSION_STORAGE_NAMESPACE_MISMATCH);
-    return false;
-  }
-
-  // If we don't want to use prerenders at all, we are done.
   // For bookkeeping purposes, we need to mark this WebContents to
   // reflect that it would have been prerendered.
   if (GetMode() == PRERENDER_MODE_EXPERIMENT_NO_USE_GROUP) {
     MarkWebContentsAsWouldBePrerendered(web_contents);
     prerender_contents.release()->Destroy(FINAL_STATUS_WOULD_HAVE_BEEN_USED);
     return false;
   }
 
   int child_id, route_id;
   CHECK(prerender_contents->GetChildId(&child_id));
   CHECK(prerender_contents->GetRouteId(&route_id));
 
   // Try to set the prerendered page as used, so any subsequent attempts to
   // cancel on other threads will fail.  If this fails because the prerender
   // was already cancelled, possibly on another thread, fail.
   if (!prerender_tracker_->TryUse(child_id, route_id))
     return false;
 
+  // At this point, we've determined that we will use the prerender.
+
   if (!prerender_contents->load_start_time().is_null()) {
     histograms_->RecordTimeUntilUsed(GetCurrentTimeTicks() -
                                      prerender_contents->load_start_time(),
                                      GetMaxAge());
   }
 
   histograms_->RecordPerSessionCount(++prerenders_per_session_count_);
   histograms_->RecordUsedPrerender(prerender_contents->origin());
   prerender_contents->set_final_status(FINAL_STATUS_USED);
 
+  RenderViewHost* new_render_view_host =
+      prerender_contents->prerender_contents()->web_contents()->
+          GetRenderViewHost();
   new_render_view_host->Send(
       new PrerenderMsg_SetIsPrerendering(new_render_view_host->GetRoutingID(),
                                          false));
 
+  // Start pending prerender requests from the PrerenderContents, if there are
+  // any.
+  prerender_contents->StartPendingPrerenders();
+
   TabContents* new_tab_contents =
       prerender_contents->ReleasePrerenderContents();
   TabContents* old_tab_contents = TabContents::FromWebContents(web_contents);
   DCHECK(new_tab_contents);
   DCHECK(old_tab_contents);
 
   MarkWebContentsAsPrerendered(new_tab_contents->web_contents());
 
   // Merge the browsing history.
   new_tab_contents->web_contents()->GetController().CopyStateFromAndPrune(
@@ skipping 12 matching lines @@
   }
 
   // Update PPLT metrics:
   // If the tab has finished loading, record a PPLT of 0.
   // If the tab is still loading, reset its start time to the current time.
   PrerenderTabHelper* prerender_tab_helper =
       new_tab_contents->prerender_tab_helper();
   DCHECK(prerender_tab_helper != NULL);
   prerender_tab_helper->PrerenderSwappedIn();
 
-  // Start pending prerender requests from the PrerenderContents, if there are
-  // any.
-  prerender_contents->StartPendingPrerenders();
-
   if (old_tab_contents->web_contents()->NeedToFireBeforeUnload()) {
     // Schedule the delete to occur after the tab has run its unload handlers.
     on_close_tab_contents_deleters_.push_back(
         new OnCloseTabContentsDeleter(this, old_tab_contents));
     old_tab_contents->web_contents()->GetRenderViewHost()->
         FirePageBeforeUnload(false);
   } else {
     // No unload handler to run, so delete asap.
     ScheduleDeleteOldTabContents(old_tab_contents, NULL);
   }
 
   // TODO(cbentzel): Should prerender_contents move to the pending delete
   //                 list, instead of deleting directly here?
   AddToHistory(prerender_contents.get());
   RecordNavigation(url);
   return true;
 }
 
 void PrerenderManager::MoveEntryToPendingDelete(PrerenderContents* entry,
                                                 FinalStatus final_status) {
   DCHECK(CalledOnValidThread());
   DCHECK(entry);
   // Confirm this entry has not already been moved to the pending delete list.
   DCHECK_EQ(0, std::count(pending_delete_list_.begin(),
                           pending_delete_list_.end(), entry));
 
-  for (PrerenderContentsDataList::iterator it = prerender_list_.begin();
-       it != prerender_list_.end();
-       ++it) {
-    if (it->contents_ == entry) {
-      bool swapped_in_dummy_replacement = false;
+  std::list<PrerenderHandle::PrerenderData>::iterator it =
+      FindIteratorForPrerenderContents(entry);
 
-      // If this PrerenderContents is being deleted due to a cancellation,
-      // we need to create a dummy replacement for PPLT accounting purposes
-      // for the Match Complete group.
-      // This is the case if the cancellation is for any reason that would not
-      // occur in the control group case.
-      if (entry->match_complete_status() ==
-          PrerenderContents::MATCH_COMPLETE_DEFAULT &&
-          NeedMatchCompleteDummyForFinalStatus(final_status) &&
-          ActuallyPrerendering()) {
-        // TODO(tburkard): I'd like to DCHECK that we are actually prerendering.
-        // However, what if new conditions are added and
-        // NeedMatchCompleteDummyForFinalStatus, is not being updated.  Not sure
-        // what's the best thing to do here.  For now, I will just check whether
-        // we are actually prerendering.
-        entry->set_match_complete_status(
-            PrerenderContents::MATCH_COMPLETE_REPLACED);
-        if (PrerenderContents* dummy_replacement_prerender_contents =
-                CreatePrerenderContents(entry->prerender_url(),
-                                        entry->referrer(),
-                                        entry->origin(),
-                                        entry->experiment_id())) {
-          dummy_replacement_prerender_contents->set_match_complete_status(
-              PrerenderContents::MATCH_COMPLETE_REPLACEMENT_PENDING);
-          if (!dummy_replacement_prerender_contents->Init())
-            break;
-          dummy_replacement_prerender_contents->
-              AddAliasURLsFromOtherPrerenderContents(entry);
-          dummy_replacement_prerender_contents->set_match_complete_status(
-              PrerenderContents::MATCH_COMPLETE_REPLACEMENT);
-          it->contents_ = dummy_replacement_prerender_contents;
-          swapped_in_dummy_replacement = true;
-        }
-      }
-      if (!swapped_in_dummy_replacement)
-        prerender_list_.erase(it);
-      break;
+  // If this PrerenderContents is being deleted due to a cancellation,
+  // we need to create a dummy replacement for PPLT accounting purposes
+  // for the Match Complete group.
+  // This is the case if the cancellation is for any reason that would not
+  // occur in the control group case.
+  if (it != active_prerender_list_.end()) {
+    if (entry->match_complete_status() ==
+            PrerenderContents::MATCH_COMPLETE_DEFAULT &&
+        NeedMatchCompleteDummyForFinalStatus(final_status) &&
+        ActuallyPrerendering()) {
+      // TODO(tburkard): I'd like to DCHECK that we are actually prerendering.
+      // However, what if new conditions are added and
+      // NeedMatchCompleteDummyForFinalStatus, is not being updated.  Not sure
+      // what's the best thing to do here.  For now, I will just check whether
+      // we are actually prerendering.
+      entry->set_match_complete_status(
+          PrerenderContents::MATCH_COMPLETE_REPLACED);
+      PrerenderContents* dummy_replacement_prerender_contents =
+          CreatePrerenderContents(entry->prerender_url(), entry->referrer(),
+                                  entry->origin(), entry->experiment_id());
+      dummy_replacement_prerender_contents->MakeIntoDummyReplacementOf(entry);
+      DCHECK(dummy_replacement_prerender_contents);
+
+      dummy_replacement_prerender_contents->set_match_complete_status(
+          PrerenderContents::MATCH_COMPLETE_REPLACEMENT_PENDING);
+      DCHECK(dummy_replacement_prerender_contents->Init());
+      dummy_replacement_prerender_contents->
+          AddAliasURLsFromOtherPrerenderContents(entry);
+      dummy_replacement_prerender_contents->set_match_complete_status(
+          PrerenderContents::MATCH_COMPLETE_REPLACEMENT);
+
+      it->contents = dummy_replacement_prerender_contents;
+    } else {
+      InvalidatePrerenderHandlesForPrerenderData(*it);
+      active_prerender_list_.erase(it);

[mmenke, 2012/07/10 18:01:13]

I'd suggest replacing InvalidatePrerenderHandlesForPrerenderData(*it) with
DeletePrerenderData(list_, *it), and have it do the erasing as well.  I figure
if two operations must always be done together or we could end up with a
difficult to detect leak, it's best to couple them in a function, if possible.

[gavinp, 2012/07/11 17:04:00]

Done, but mooted if we go with the ptr in the struct (see below).

     }
   }
+
   AddToHistory(entry);
   pending_delete_list_.push_back(entry);
 
   // Destroy the old WebContents relatively promptly to reduce resource usage,
   // and in the case of HTML5 media, reduce the change of playing any sound.
   PostCleanupTask();
 }
 
 // static
 void PrerenderManager::RecordPerceivedPageLoadTime(
@@ skipping 90 matching lines @@
 }
 
 // static
 bool PrerenderManager::IsNoUseGroup() {
   return GetMode() == PRERENDER_MODE_EXPERIMENT_NO_USE_GROUP;
 }
 
 bool PrerenderManager::IsWebContentsPrerendering(
     WebContents* web_contents) const {
   DCHECK(CalledOnValidThread());
-  for (PrerenderContentsDataList::const_iterator it = prerender_list_.begin();
-       it != prerender_list_.end();
+  for (std::list<PrerenderHandle::PrerenderData>::const_iterator it =
+           active_prerender_list_.begin();
+       it != active_prerender_list_.end();
        ++it) {
-    TabContents* prerender_tab_contents = it->contents_->prerender_contents();
+    TabContents* prerender_tab_contents = it->contents->prerender_contents();
     if (prerender_tab_contents &&
         prerender_tab_contents->web_contents() == web_contents) {
       return true;
     }
   }
 
   // Also look through the pending-deletion list.
   for (std::list<PrerenderContents*>::const_iterator it =
            pending_delete_list_.begin();
        it != pending_delete_list_.end();
        ++it) {
     TabContents* prerender_tab_contents = (*it)->prerender_contents();
     if (prerender_tab_contents &&
         prerender_tab_contents->web_contents() == web_contents)
       return true;
   }
 
   return false;
 }
 
-bool PrerenderManager::DidPrerenderFinishLoading(const GURL& url) const {
-  DCHECK(CalledOnValidThread());
-  PrerenderContents* contents = FindEntry(url);
-  return contents ? contents->has_finished_loading() : false;
-}
-
 void PrerenderManager::MarkWebContentsAsPrerendered(WebContents* web_contents) {
   DCHECK(CalledOnValidThread());
   prerendered_tab_contents_set_.insert(web_contents);
 }
 
 void PrerenderManager::MarkWebContentsAsWouldBePrerendered(
     WebContents* web_contents) {
   DCHECK(CalledOnValidThread());
   would_be_prerendered_map_[web_contents] = true;
 }
@@ skipping 95 matching lines @@
   histograms_->RecordFinalStatus(origin,
                                  experiment_id,
                                  mc_status,
                                  final_status);
 }
 
 void PrerenderManager::AddCondition(const PrerenderCondition* condition) {
   prerender_conditions_.push_back(condition);
 }
 
-bool PrerenderManager::IsPendingEntry(const GURL& url) const {
-  DCHECK(CalledOnValidThread());
-  for (PrerenderContentsDataList::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) const {
-  DCHECK(CalledOnValidThread());
-  return (FindEntry(url) != NULL);
-}
-
 void PrerenderManager::RecordNavigation(const GURL& url) {
   DCHECK(CalledOnValidThread());
 
   navigations_.push_back(NavigationRecord(url, GetCurrentTimeTicks()));
   CleanUpOldNavigations();
 }
 
 // protected
 void PrerenderManager::SetPrerenderContentsFactory(
     PrerenderContents::Factory* prerender_contents_factory) {
   DCHECK(CalledOnValidThread());
   prerender_contents_factory_.reset(prerender_contents_factory);
 }
 
 void PrerenderManager::DoShutdown() {
   DestroyAllContents(FINAL_STATUS_MANAGER_SHUTDOWN);
   STLDeleteElements(&prerender_conditions_);
   on_close_tab_contents_deleters_.reset();
   profile_ = NULL;
+
+  DCHECK(active_prerender_list_.empty());
+  DCHECK(pending_prerender_list_.empty());
+  DCHECK(prerender_weak_ptr_factory_map_.empty());
 }
 
 // private
-bool PrerenderManager::AddPrerender(
+PrerenderHandle* PrerenderManager::AddPrerender(
     Origin origin,
     int process_id,
     const GURL& url_arg,
     const content::Referrer& referrer,
     gfx::Size size,
     SessionStorageNamespace* session_storage_namespace) {
   DCHECK(CalledOnValidThread());
 
   if (!IsEnabled())
-    return false;
+    return NULL;
 
   if (origin == ORIGIN_LINK_REL_PRERENDER &&
       IsGoogleSearchResultURL(referrer.url)) {
     origin = ORIGIN_GWS_PRERENDER;
   }
 
   DeleteOldEntries();
   DeletePendingDeleteEntries();
 
   GURL url = url_arg;
   GURL alias_url;
   uint8 experiment = GetQueryStringBasedExperiment(url_arg);
   bool control_group_behavior =
       IsControlGroup() || IsControlGroupExperiment(experiment);
   if (control_group_behavior &&
       MaybeGetQueryStringBasedAliasURL(url, &alias_url)) {
     url = alias_url;
   }
 
   // From here on, we will record a FinalStatus so we need to register with the
   // histogram tracking.
   histograms_->RecordPrerender(origin, url_arg);
 
-  if (PrerenderContentsData* prerender_contents_data = FindEntryData(url)) {
-    ++prerender_contents_data->active_count_;
+  if (PrerenderHandle::PrerenderData* preexisting_prerender_data =
+          FindPrerenderData(url, session_storage_namespace)) {
     RecordFinalStatus(origin, experiment, FINAL_STATUS_DUPLICATE);
-    return true;
+    ++preexisting_prerender_data->instance_count;
+    return CreatePrerenderHandleForPrerenderData(preexisting_prerender_data);
   }
 
   // Do not prerender if there are too many render processes, and we would
   // have to use an existing one.  We do not want prerendering to happen in
   // a shared process, so that we can always reliably lower the CPU
   // priority for prerendering.
   // In single-process mode, ShouldTryToUseExistingProcessHost() always returns
   // true, so that case needs to be explicitly checked for.
   // TODO(tburkard): Figure out how to cancel prerendering in the opposite
   // case, when a new tab is added to a process used for prerendering.
   // On Android we do reuse processes as we have a limited number of them and we
   // still want the benefits of prerendering even when several tabs are open.
 #if !defined(OS_ANDROID)
   if (content::RenderProcessHost::ShouldTryToUseExistingProcessHost(
           profile_, url) &&
       !content::RenderProcessHost::run_renderer_in_process()) {
     RecordFinalStatus(origin, experiment, FINAL_STATUS_TOO_MANY_PROCESSES);
-    return false;
+    return NULL;
   }
 #endif
 
   // Check if enough time has passed since the last prerender.
   if (!DoesRateLimitAllowPrerender()) {
     // Cancel the prerender. We could add it to the pending prerender list but
     // this doesn't make sense as the next prerender request will be triggered
     // by a navigation and is unlikely to be the same site.
     RecordFinalStatus(origin, experiment, FINAL_STATUS_RATE_LIMIT_EXCEEDED);
-    return false;
+    return NULL;
   }
 
   PrerenderContents* prerender_contents = CreatePrerenderContents(
       url, referrer, origin, experiment);
   if (!prerender_contents || !prerender_contents->Init())
-    return false;
+    return NULL;
 
   histograms_->RecordPrerenderStarted(origin);
 
   // TODO(cbentzel): Move invalid checks here instead of PrerenderContents?
-  PrerenderContentsData data(prerender_contents, GetCurrentTime());
+  active_prerender_list_.push_back(
+      PrerenderHandle::PrerenderData(this, prerender_contents));
 
-  prerender_list_.push_back(data);
+  PrerenderHandle* prerender_handle =
+      CreatePrerenderHandleForPrerenderData(&active_prerender_list_.back());
 
   last_prerender_start_time_ = GetCurrentTimeTicks();
 
   if (size.IsEmpty())
     size = config_.default_tab_bounds.size();
 
-  data.contents_->StartPrerendering(process_id, size, session_storage_namespace,
-                                    control_group_behavior);
+  prerender_contents->StartPrerendering(process_id, size,
+                                        session_storage_namespace,
+                                        control_group_behavior);
 
-  while (prerender_list_.size() > config_.max_elements) {
-    data = prerender_list_.front();
-    prerender_list_.pop_front();
-    data.contents_->Destroy(FINAL_STATUS_EVICTED);
+  while (active_prerender_list_.size() > config_.max_elements) {
+    prerender_contents = active_prerender_list_.front().contents;
+    DCHECK(prerender_contents);
+    prerender_contents->Destroy(FINAL_STATUS_EVICTED);
   }
+
   StartSchedulingPeriodicCleanups();
-  return true;
-}
-
-PrerenderContents* PrerenderManager::GetEntry(const GURL& url) {
-  return GetEntryButNotSpecifiedWC(url, NULL);
-}
-
-PrerenderContents* PrerenderManager::GetEntryButNotSpecifiedWC(
-    const GURL& url,
-    WebContents* wc) {
-  DCHECK(CalledOnValidThread());
-  DeleteOldEntries();
-  DeletePendingDeleteEntries();
-  for (PrerenderContentsDataList::iterator it = prerender_list_.begin();
-       it != prerender_list_.end();
-       ++it) {
-    PrerenderContents* prerender_contents = it->contents_;
-    if (prerender_contents->MatchesURL(url, NULL) &&
-        !IsNoSwapInExperiment(prerender_contents->experiment_id())) {
-      if (!prerender_contents->prerender_contents() ||
-          !wc ||
-          prerender_contents->prerender_contents()->web_contents() != wc) {
-        prerender_list_.erase(it);
-        return prerender_contents;
-      }
-    }
-  }
-  // Entry not found.
-  return NULL;
+  return prerender_handle;
 }
 
 void PrerenderManager::StartSchedulingPeriodicCleanups() {
   DCHECK(CalledOnValidThread());
   if (repeating_timer_.IsRunning())
     return;
   repeating_timer_.Start(FROM_HERE,
       base::TimeDelta::FromMilliseconds(kPeriodicCleanupIntervalMs),
       this,
       &PrerenderManager::PeriodicCleanup);
 }
 
-void PrerenderManager::MaybeStopSchedulingPeriodicCleanups() {
-  if (!prerender_list_.empty())
-    return;
-
+void PrerenderManager::StopSchedulingPeriodicCleanups() {
   DCHECK(CalledOnValidThread());
   repeating_timer_.Stop();
 }
 
 void PrerenderManager::PeriodicCleanup() {
   DCHECK(CalledOnValidThread());
   DeleteOldTabContents();
   DeleteOldEntries();
+  if (active_prerender_list_.empty())
+    StopSchedulingPeriodicCleanups();
 
   // Grab a copy of the current PrerenderContents pointers, so that we
   // will not interfere with potential deletions of the list.
   std::vector<PrerenderContents*> prerender_contents;
-  for (PrerenderContentsDataList::iterator it = prerender_list_.begin();
-       it != prerender_list_.end();
-       ++it) {
-    DCHECK(it->contents_);
-    prerender_contents.push_back(it->contents_);
+  prerender_contents.reserve(active_prerender_list_.size());
+  for (std::list<PrerenderHandle::PrerenderData>::iterator
+          it = active_prerender_list_.begin();
+      it != active_prerender_list_.end();
+      ++it) {
+    prerender_contents.push_back(it->contents);
   }
-  for (std::vector<PrerenderContents*>::iterator it =
-           prerender_contents.begin();
-       it != prerender_contents.end();
-       ++it) {
-    (*it)->DestroyWhenUsingTooManyResources();
-  }
+  std::for_each(prerender_contents.begin(), prerender_contents.end(),
+                std::mem_fun(
+                    &PrerenderContents::DestroyWhenUsingTooManyResources));
 
   DeletePendingDeleteEntries();
 }
 
 void PrerenderManager::PostCleanupTask() {
   DCHECK(CalledOnValidThread());
   MessageLoop::current()->PostTask(
       FROM_HERE,
       base::Bind(&PrerenderManager::PeriodicCleanup,
                  weak_factory_.GetWeakPtr()));
 }
 
 base::TimeDelta PrerenderManager::GetMaxAge() const {
   return (GetMode() == PRERENDER_MODE_EXPERIMENT_5MIN_TTL_GROUP ?
       base::TimeDelta::FromSeconds(300) : config_.max_age);
 }
 
-bool PrerenderManager::IsPrerenderElementFresh(const base::Time start) const {
+bool PrerenderManager::IsPrerenderFresh(const base::TimeTicks start) const {
   DCHECK(CalledOnValidThread());
-  base::Time now = GetCurrentTime();
-  return (now - start < GetMaxAge());
+  return GetCurrentTimeTicks() - start < GetMaxAge();
 }
 
 void PrerenderManager::DeleteOldEntries() {
   DCHECK(CalledOnValidThread());
-  while (!prerender_list_.empty()) {
-    PrerenderContentsData data = prerender_list_.front();
-    if (IsPrerenderElementFresh(data.start_time_))
+  while (!active_prerender_list_.empty()) {
+    PrerenderContents* contents = active_prerender_list_.front().contents;
+    DCHECK(contents);
+    if (IsPrerenderFresh(contents->load_start_time()))
       return;
-    data.contents_->Destroy(FINAL_STATUS_TIMED_OUT);
+    contents->Destroy(FINAL_STATUS_TIMED_OUT);
   }
-  MaybeStopSchedulingPeriodicCleanups();
 }
 
 base::Time PrerenderManager::GetCurrentTime() const {
   return base::Time::Now();
 }
 
 base::TimeTicks PrerenderManager::GetCurrentTimeTicks() const {
   return base::TimeTicks::Now();
 }
 
 PrerenderContents* PrerenderManager::CreatePrerenderContents(
     const GURL& url,
     const content::Referrer& referrer,
     Origin origin,
     uint8 experiment_id) {
   DCHECK(CalledOnValidThread());
   return prerender_contents_factory_->CreatePrerenderContents(
       this, prerender_tracker_, profile_, url,
       referrer, origin, experiment_id);
 }
 
 void PrerenderManager::DeletePendingDeleteEntries() {
   while (!pending_delete_list_.empty()) {
     PrerenderContents* contents = pending_delete_list_.front();
     pending_delete_list_.pop_front();
     delete contents;
   }
 }
 
-PrerenderManager::PrerenderContentsData* PrerenderManager::FindEntryData(
-    const GURL& url) {
-  DCHECK(CalledOnValidThread());
-  PrerenderContentsDataList::iterator it = FindPrerenderContentsForURL(url);
-  if (it == prerender_list_.end())
-    return NULL;
-  PrerenderContentsData& prerender_contents_data = *it;
-  return &prerender_contents_data;
+PrerenderHandle* PrerenderManager::CreatePrerenderHandleForPrerenderData(
+    PrerenderHandle::PrerenderData* prerender_data) {
+  PrerenderWeakPtrFactoryMap::value_type map_value(prerender_data, NULL);
+  std::pair<PrerenderWeakPtrFactoryMap::iterator, bool>
+      insert_result = prerender_weak_ptr_factory_map_.insert(map_value);
+  if (insert_result.second)
+    insert_result.first->second =
+        new base::WeakPtrFactory<PrerenderHandle::PrerenderData>(
+            prerender_data);
+  DCHECK(insert_result.first->second);
+  base::WeakPtr<PrerenderHandle::PrerenderData> weak_prerender_data =
+      insert_result.first->second->GetWeakPtr();
+  return new PrerenderHandle(weak_prerender_data);
 }
 
-PrerenderContents* PrerenderManager::FindEntry(const GURL& url) const {
-  DCHECK(CalledOnValidThread());
-  for (PrerenderContentsDataList::const_iterator it = prerender_list_.begin();
-       it != prerender_list_.end();
+void PrerenderManager::InvalidatePrerenderHandlesForPrerenderData(

[mmenke, 2012/07/10 18:01:13]

I think that this is pretty ugly.  My suggestion (And I'm completely open to
push back/discussion on this) would be to make PrerenderData have a pointer to
the factory.  I'd also switch PrerenderData to being an inner class of
PrerenderManager at the same time, since proper use of PrerenderData would then
be more dependent on PrerenderManager than PrerenderHandle.

My reasoning is basically just that the fewer redundant stl containers we have,
the simpler things are.

[gavinp, 2012/07/11 17:04:00]

Done. Please look it over and let me know what you think about the struct and
its podness.

+    const PrerenderHandle::PrerenderData& prerender_data) {
+  PrerenderWeakPtrFactoryMap::iterator it =
+      prerender_weak_ptr_factory_map_.find(&prerender_data);
+  if (it != prerender_weak_ptr_factory_map_.end()) {
+    delete it->second;
+    prerender_weak_ptr_factory_map_.erase(it);
+  }
+}
+
+PrerenderHandle::PrerenderData* PrerenderManager::FindPrerenderData(
+    const GURL& url,
+    const SessionStorageNamespace* session_storage_namespace) {
+  for (std::list<PrerenderHandle::PrerenderData>::iterator
+           it = active_prerender_list_.begin();
+       it != active_prerender_list_.end();
        ++it) {
-    if (it->contents_->MatchesURL(url, NULL))
-      return it->contents_;
+    PrerenderContents* prerender_contents = it->contents;
+    if (prerender_contents->Matches(url, session_storage_namespace))
+      return &(*it);
   }
-  // Entry not found.
   return NULL;
 }
 
-PrerenderManager::PrerenderContentsDataList::iterator
-    PrerenderManager::FindPrerenderContentsForChildRouteIdPair(
-        const std::pair<int, int>& child_route_id_pair) {
-  PrerenderContentsDataList::iterator it = prerender_list_.begin();
-  for (; it != prerender_list_.end(); ++it) {
-    PrerenderContents* prerender_contents = it->contents_;
+PrerenderHandle::PrerenderData*
+PrerenderManager::FindPrerenderDataForChildAndRoute(
+    const int child_id, const int route_id) {
+  for (std::list<PrerenderHandle::PrerenderData>::iterator
+           it = active_prerender_list_.begin();
+       it != active_prerender_list_.end();
+       ++it) {
+    PrerenderContents* prerender_contents = it->contents;
 
-    int child_id;
-    int route_id;
-    bool has_child_id = prerender_contents->GetChildId(&child_id);
-    bool has_route_id = has_child_id &&
-                        prerender_contents->GetRouteId(&route_id);
+    int contents_child_id;
+    if (!prerender_contents->GetChildId(&contents_child_id))
+      continue;
+    int contents_route_id;
+    if (!prerender_contents->GetRouteId(&contents_route_id))
+      continue;
 
-    if (has_child_id && has_route_id &&
-        child_id == child_route_id_pair.first &&
-        route_id == child_route_id_pair.second) {
-      break;
-    }
+    if (contents_child_id == child_id && contents_route_id == route_id)
+      return &(*it);
   }
-  return it;
+  return NULL;
 }
 
-PrerenderManager::PrerenderContentsDataList::iterator
-    PrerenderManager::FindPrerenderContentsForURL(const GURL& url) {
-  for (PrerenderContentsDataList::iterator it = prerender_list_.begin();
-       it != prerender_list_.end(); ++it) {
-    if (it->contents_->MatchesURL(url, NULL))
+std::list<PrerenderHandle::PrerenderData>::iterator
+PrerenderManager::FindIteratorForPrerenderContents(
+    PrerenderContents* prerender_contents) {
+  for (std::list<PrerenderHandle::PrerenderData>::iterator
+           it = active_prerender_list_.begin();
+       it != active_prerender_list_.end();
+       ++it) {
+    if (prerender_contents == it->contents)
       return it;
   }
-  return prerender_list_.end();
+  return active_prerender_list_.end();
 }
 
 bool PrerenderManager::DoesRateLimitAllowPrerender() const {
   DCHECK(CalledOnValidThread());
   base::TimeDelta elapsed_time =
       GetCurrentTimeTicks() - last_prerender_start_time_;
   histograms_->RecordTimeBetweenPrerenderRequests(elapsed_time);
   if (!config_.rate_limit_enabled)
     return true;
   return elapsed_time >
@@ skipping 41 matching lines @@
 void PrerenderManager::AddToHistory(PrerenderContents* contents) {
   PrerenderHistory::Entry entry(contents->prerender_url(),
                                 contents->final_status(),
                                 contents->origin(),
                                 base::Time::Now());
   prerender_history_->AddEntry(entry);
 }
 
 Value* PrerenderManager::GetActivePrerendersAsValue() const {
   ListValue* list_value = new ListValue();
-  for (PrerenderContentsDataList::const_iterator it = prerender_list_.begin();
-       it != prerender_list_.end();
+  for (std::list<PrerenderHandle::PrerenderData>::const_iterator it =
+           active_prerender_list_.begin();
+       it != active_prerender_list_.end();
        ++it) {
-    Value* prerender_value = it->contents_->GetAsValue();
-    if (!prerender_value)
-      continue;
-    list_value->Append(prerender_value);
+    if (Value* prerender_value = it->contents->GetAsValue())
+      list_value->Append(prerender_value);
   }
   return list_value;
 }
 
 void PrerenderManager::DestroyAllContents(FinalStatus final_status) {
   DeleteOldTabContents();
-  while (!prerender_list_.empty()) {
-    PrerenderContentsData data = prerender_list_.front();
-    prerender_list_.pop_front();
-    data.contents_->Destroy(final_status);
+  while (!active_prerender_list_.empty()) {
+    PrerenderContents* contents = active_prerender_list_.front().contents;
+    contents->Destroy(final_status);
   }
   DeletePendingDeleteEntries();
 }
 
 void PrerenderManager::DestroyAndMarkMatchCompleteAsUsed(
     PrerenderContents* prerender_contents,
     FinalStatus final_status) {
   prerender_contents->set_match_complete_status(
       PrerenderContents::MATCH_COMPLETE_REPLACED);
   histograms_->RecordFinalStatus(prerender_contents->origin(),
@@ skipping 38 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
+