Add SwappedOut to TabContentsDelegate to allow us to correctly delete TabContents.

chrome/browser/prerender/prerender_manager.cc

 // Copyright (c) 2011 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"
 #include "base/logging.h"
+#include "base/metrics/histogram.h"
 #include "base/stl_util.h"
 #include "base/time.h"
 #include "base/utf_string_conversions.h"
 #include "base/values.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/favicon/favicon_tab_helper.h"
 #include "chrome/browser/history/top_sites.h"
 #include "chrome/browser/prerender/prerender_condition.h"
 #include "chrome/browser/prerender/prerender_contents.h"
 #include "chrome/browser/prerender/prerender_field_trial.h"
@@ skipping 50 matching lines @@
   "OPTIONS",
   "POST",
   "TRACE",
 };
 
 // Length of prerender history, for display in chrome://net-internals
 const int kHistoryLength = 100;
 
 }  // namespace
 
-class PrerenderManager::OnCloseTabContentsDeleter : public TabContentsDelegate {
+class PrerenderManager::OnCloseTabContentsDeleter
+    : public TabContentsDelegate,
+      public SupportsWeakPtr<PrerenderManager::OnCloseTabContentsDeleter> {
  public:
   OnCloseTabContentsDeleter(PrerenderManager* manager,
                             TabContentsWrapper* tab)
       : manager_(manager),
         tab_(tab) {
     tab_->tab_contents()->set_delegate(this);
+    MessageLoop::current()->PostDelayedTask(FROM_HERE,
+        base::Bind(&OnCloseTabContentsDeleter::ScheduleTabContentsForDeletion,
+                   this->AsWeakPtr(), true), kDeleteWithExtremePrejudiceTimeMs);
   }
 
   virtual void CloseContents(TabContents* source) OVERRIDE {
-    tab_->tab_contents()->set_delegate(NULL);
-    manager_->ScheduleDeleteOldTabContents(tab_.release(), this);
+    DCHECK_EQ(tab_->tab_contents(), source);
+    ScheduleTabContentsForDeletion(false);
+  }
+
+  virtual void SwappedOut(TabContents* source) OVERRIDE {
+    DCHECK_EQ(tab_->tab_contents(), source);
+    ScheduleTabContentsForDeletion(false);
   }
 
   virtual bool ShouldSuppressDialogs() OVERRIDE {
     return true;
   }
 
  private:
+  static const int kDeleteWithExtremePrejudiceTimeMs = 3000;
+
+  void ScheduleTabContentsForDeletion(bool timeout) {
+    tab_->tab_contents()->set_delegate(NULL);
+    manager_->ScheduleDeleteOldTabContents(tab_.release(), this);
+    UMA_HISTOGRAM_BOOLEAN("Prerender.TabContentsDeleterTimeout", timeout);
+  }
+
   PrerenderManager* manager_;
   scoped_ptr<TabContentsWrapper> tab_;
 
   DISALLOW_COPY_AND_ASSIGN(OnCloseTabContentsDeleter);
 };
 
 // static
 int PrerenderManager::prerenders_per_session_count_ = 0;
 
 // static
@@ skipping 948 matching lines @@
   if (!render_process_host || !render_process_host->browser_context())
     return NULL;
   Profile* profile = Profile::FromBrowserContext(
       render_process_host->browser_context());
   if (!profile)
     return NULL;
   return PrerenderManagerFactory::GetInstance()->GetForProfile(profile);
 }
 
 }  // namespace prerender