Avoid doing periodic prerender cleanup when there are no contents.

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 <string>
 #include <vector>
@@ skipping 672 matching lines @@
 
   // If this PrerenderContents is being deleted due to a cancellation any time
   // after the prerender has started then 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->prerendering_has_started() &&
       entry->match_complete_status() ==
           PrerenderContents::MATCH_COMPLETE_DEFAULT &&
       NeedMatchCompleteDummyForFinalStatus(final_status) &&
-      ActuallyPrerendering()) {
+      ActuallyPrerendering() &&
+      GetMode() == PRERENDER_MODE_EXPERIMENT_MATCH_COMPLETE_GROUP) {
     // 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.
     (*it)->MakeIntoMatchCompleteReplacement();
   } else {
     to_delete_prerenders_.push_back(*it);
     (*it)->ClearPendingSwap();
     active_prerenders_.weak_erase(it);
@@ skipping 52 matching lines @@
     case PRERENDER_MODE_EXPERIMENT_PRERENDER_GROUP:
       return "_Enabled";
     case PRERENDER_MODE_EXPERIMENT_CONTROL_GROUP:
       return "_Control";
     case PRERENDER_MODE_EXPERIMENT_MULTI_PRERENDER_GROUP:
       return "_Multi";
     case PRERENDER_MODE_EXPERIMENT_15MIN_TTL_GROUP:
       return "_15MinTTL";
     case PRERENDER_MODE_EXPERIMENT_NO_USE_GROUP:
       return "_NoUse";
+    case PRERENDER_MODE_EXPERIMENT_MATCH_COMPLETE_GROUP:
+      return "_MatchComplete";
     case PRERENDER_MODE_MAX:
     default:
       NOTREACHED() << "Invalid PrerenderManager mode.";
       break;
   }
   return "";
 }
 
 // static
 bool PrerenderManager::IsPrerenderingPossible() {
@@ skipping 1109 matching lines @@
     content::RenderProcessHost* host) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   prerender_process_hosts_.erase(host);
   BrowserThread::PostTask(
       BrowserThread::IO, FROM_HERE,
       base::Bind(&PrerenderTracker::RemovePrerenderCookieStoreOnIOThread,
                  base::Unretained(prerender_tracker()), host->GetID(), false));
 }
 
 }  // namespace prerender