Attempt at a crash fix in LazyBackgroundTaskQueue::ProcessPendingTasks.

chrome/browser/extensions/lazy_background_task_queue.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/extensions/lazy_background_task_queue.h"
 
 #include "base/callback.h"
 #include "base/message_loop.h"
 #include "chrome/browser/extensions/extension_host.h"
 #include "chrome/browser/extensions/extension_process_manager.h"
@@ skipping 97 matching lines @@
       !extension->has_lazy_background_page())
     return;
 
   PendingTasksKey key(profile, extension->id());
   PendingTasksMap::iterator map_it = pending_tasks_.find(key);
   if (map_it == pending_tasks_.end()) {
     CHECK(!host);  // lazy page should not load without any pending tasks
     return;
   }
 
-  PendingTasksList* tasks = map_it->second.get();
-  for (PendingTasksList::const_iterator it = tasks->begin();
-       it != tasks->end(); ++it) {
+  // Swap the pending tasks to a temporary, to avoid problems if the task
+  // list is modified during processing.
+  PendingTasksList tasks;
+  tasks.swap(*map_it->second);
+  for (PendingTasksList::const_iterator it = tasks.begin();
+       it != tasks.end(); ++it) {
     it->Run(host);
   }
 
-  tasks->clear();
-  pending_tasks_.erase(map_it);
+  pending_tasks_.erase(key);
 
   // Balance the keepalive in AddPendingTask. Note we don't do this on a
   // failure to load, because the keepalive count is reset in that case.
   if (host) {
     ExtensionSystem::Get(profile)->process_manager()->
         DecrementLazyKeepaliveCount(extension);
   }
 }
 
 void LazyBackgroundTaskQueue::Observe(
@@ skipping 46 matching lines @@
       }
       break;
     }
     default:
       NOTREACHED();
       break;
   }
 }
 
 }  // namespace extensions