Prevent a crash in TaskManagerWindowController by nil-ing the dataSource and delegate in dealloc.

chrome/browser/cocoa/task_manager_mac.mm

 // Copyright (c) 2010 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/cocoa/task_manager_mac.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "app/l10n_util_mac.h"
@@ skipping 177 matching lines @@
 
 - (void)awakeFromNib {
   [self setUpTableColumns];
   [self setUpTableHeaderContextMenu];
   [self adjustSelectionAndEndProcessButton];
 
   [tableView_ setDoubleAction:@selector(selectDoubleClickedTab:)];
   [tableView_ sizeToFit];
 }
 
+- (void)dealloc {
+  [tableView_ setDelegate:nil];
+  [tableView_ setDataSource:nil];
+  [super dealloc];
+}
+
 // Adds a column which has the given string id as title. |isVisible| specifies
 // if the column is initially visible.
 - (NSTableColumn*)addColumnWithId:(int)columnId visible:(BOOL)isVisible {
   scoped_nsobject<NSTableColumn> column([[NSTableColumn alloc]
       initWithIdentifier:[NSNumber numberWithInt:columnId]]);
 
   NSTextAlignment textAlignment = columnId == IDS_TASK_MANAGER_PAGE_COLUMN ?
       NSLeftTextAlignment : NSRightTextAlignment;
 
   [[column.get() headerCell]
@@ skipping 359 matching lines @@
 void TaskManagerMac::Show() {
   if (instance_) {
     // If there's a Task manager window open already, just activate it.
     [[instance_->window_controller_ window]
         makeKeyAndOrderFront:instance_->window_controller_];
   } else {
     instance_ = new TaskManagerMac(TaskManager::GetInstance());
     instance_->model_->StartUpdating();
   }
 }