Convert main NTP panel to UIViewController.

ios/chrome/browser/ui/browser_view_controller.mm

 // Copyright 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.
 
 #import "ios/chrome/browser/ui/browser_view_controller.h"
 
 #import <AssetsLibrary/AssetsLibrary.h>
 #import <MobileCoreServices/MobileCoreServices.h>
 #import <PassKit/PassKit.h>
 #import <Photos/Photos.h>
@@ skipping 3018 matching lines @@
     NewTabPageController* pageController =
         [[NewTabPageController alloc] initWithUrl:url
                                            loader:self
                                           focuser:_toolbarController
                                       ntpObserver:self
                                      browserState:_browserState
                                        colorCache:_dominantColorCache
                                webToolbarDelegate:self
                                          tabModel:_model];
     pageController.swipeRecognizerProvider = self.sideSwipeController;
+    pageController.parentViewController = self;
 
     // Panel is always NTP for iPhone.
     NewTabPage::PanelIdentifier panelType = NewTabPage::kMostVisitedPanel;
 
     if (IsIPadIdiom()) {
       // New Tab Page can have multiple panels. Each panel is addressable
       // by a #fragment, e.g. chrome://newtab/#most_visited takes user to
       // the Most Visited page, chrome://newtab/#bookmarks takes user to
       // the Bookmark Manager, etc.
       // The utility functions NewTabPage::IdentifierFromFragment() and
@@ skipping 2134 matching lines @@
 
 - (UIView*)voiceSearchButton {
   return _voiceSearchButton;
 }
 
 - (id<LogoAnimationControllerOwner>)logoAnimationControllerOwner {
   return [self currentLogoAnimationControllerOwner];
 }
 
 @end