[iOS Clean] Update ContextMenuItem to use a single command.

ios/clean/chrome/browser/ui/context_menu/web_context_menu_coordinator.mm

 // Copyright 2017 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.
 
 #import "ios/clean/chrome/browser/ui/context_menu/web_context_menu_coordinator.h"
 
 #include "base/logging.h"
 #import "ios/clean/chrome/browser/ui/commands/context_menu_commands.h"
 #import "ios/clean/chrome/browser/ui/context_menu/context_menu_context_impl.h"
 #import "ios/clean/chrome/browser/ui/context_menu/context_menu_mediator.h"
 #import "ios/clean/chrome/browser/ui/context_menu/context_menu_view_controller.h"
 #import "ios/shared/chrome/browser/ui/browser_list/browser.h"
 #import "ios/shared/chrome/browser/ui/commands/command_dispatcher.h"
+#import "ios/shared/chrome/browser/ui/coordinators/browser_coordinator+internal.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 @interface WebContextMenuCoordinator ()<ContextMenuCommands>
 // The menu context.
 @property(nonatomic, strong, readonly) ContextMenuContextImpl* context;
 // The view controller that displayes the context menu UI.
 @property(nonatomic, strong) ContextMenuViewController* viewController;
@@ skipping 23 matching lines @@
                           withContext:self.context];
   [self.browser->dispatcher()
       startDispatchingToTarget:self
                    forSelector:@selector(hideContextMenu:)];
   [super start];
 }
 
 - (void)stop {
   [self.browser->dispatcher() stopDispatchingToTarget:self];
   [super stop];
+  [self.parentCoordinator removeChildCoordinator:self];
 }
 
 #pragma mark - ContextMenuCommands
 
 - (void)hideContextMenu:(ContextMenuContext*)context {
   DCHECK_EQ(self.context, context);
   [self stop];
 }
 
 @end