[TaskManager] Check iterators' availabilities before manipulating them.

chrome/browser/task_manager/task_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/task_manager/task_manager.h"
 
 #include "base/bind.h"
 #include "base/i18n/number_formatting.h"
 #include "base/i18n/rtl.h"
 #include "base/prefs/pref_registry_simple.h"
@@ skipping 976 matching lines @@
   FOR_EACH_OBSERVER(TaskManagerModelObserver, observer_list_,
                     OnItemsAdded(new_entry_index, 1));
 }
 
 void TaskManagerModel::RemoveResource(Resource* resource) {
   base::ProcessHandle process = resource->GetProcess();
 
   // Find the associated group.
   GroupMap::iterator group_iter = group_map_.find(process);
   DCHECK(group_iter != group_map_.end());
+  if (group_iter == group_map_.end())
+    return;
   ResourceList& group_entries = group_iter->second;
 
   // Remove the entry from the group map.
   ResourceList::iterator iter = std::find(group_entries.begin(),
                                           group_entries.end(),
                                           resource);
   DCHECK(iter != group_entries.end());
-  group_entries.erase(iter);
+  if (iter != group_entries.end())
+    group_entries.erase(iter);
 
   // If there are no more entries for that process, do the clean-up.
   if (group_entries.empty()) {
     group_map_.erase(group_iter);
 
     // Nobody is using this process, we don't need the process metrics anymore.
     MetricsMap::iterator pm_iter = metrics_map_.find(process);
     DCHECK(pm_iter != metrics_map_.end());
     if (pm_iter != metrics_map_.end()) {
       delete pm_iter->second;
       metrics_map_.erase(process);
     }
   }
 
-  // Prepare to remove the entry from the model list.
+  // Remove the entry from the model list.
   iter = std::find(resources_.begin(), resources_.end(), resource);
   DCHECK(iter != resources_.end());
-  int index = static_cast<int>(iter - resources_.begin());
-
-  // Notify the observers that the contents will change.
-  FOR_EACH_OBSERVER(TaskManagerModelObserver, observer_list_,
-                    OnItemsToBeRemoved(index, 1));
-
-  // Now actually remove the entry from the model list.
-  resources_.erase(iter);
+  if (iter != resources_.end()) {
+    int index = static_cast<int>(iter - resources_.begin());
+    // Notify the observers that the contents will change.
+    FOR_EACH_OBSERVER(TaskManagerModelObserver, observer_list_,
+                      OnItemsToBeRemoved(index, 1));
+    // Now actually remove the entry from the model list.
+    resources_.erase(iter);
+    // Notify the table that the contents have changed.
+    FOR_EACH_OBSERVER(TaskManagerModelObserver, observer_list_,
+                      OnItemsRemoved(index, 1));
+  }
 
   // Remove the entry from the network maps.
   ResourceValueMap::iterator net_iter =
       current_byte_count_map_.find(resource);
   if (net_iter != current_byte_count_map_.end())
     current_byte_count_map_.erase(net_iter);
-
-  // Notify the table that the contents have changed.
-  FOR_EACH_OBSERVER(TaskManagerModelObserver, observer_list_,
-                    OnItemsRemoved(index, 1));
 }
 
 void TaskManagerModel::StartUpdating() {
   // Multiple StartUpdating requests may come in, and we only need to take
   // action the first time.
   update_requests_++;
   if (update_requests_ > 1)
     return;
   DCHECK_EQ(1, update_requests_);
   DCHECK_NE(TASK_PENDING, update_state_);
@@ skipping 503 matching lines @@
   params.host_desktop_type = desktop_type;
   chrome::Navigate(&params);
 }
 
 TaskManager::TaskManager()
     : model_(new TaskManagerModel(this)) {
 }
 
 TaskManager::~TaskManager() {
 }