Revert "[ios] Ensure proper shutdown of Chrome on iOS."

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 453 matching lines @@
   // finished.
   BOOL _startVoiceSearchAfterNewTabAnimation;
 
   // YES if the user interacts with the location bar.
   BOOL _locationBarHasFocus;
   // YES if a load was cancelled due to typing in the location bar.
   BOOL _locationBarEditCancelledLoad;
   // YES if waiting for a foreground tab due to expectNewForegroundTab.
   BOOL _expectingForegroundTab;
 
-  // Whether or not -shutdown has been called.
-  BOOL _isShutdown;
-
   // The ChromeBrowserState associated with this BVC.
   ios::ChromeBrowserState* _browserState;  // weak
 
   // Whether or not Incognito* is enabled.
   BOOL _isOffTheRecord;
 
   // The last point within |_contentArea| that's received a touch.
   CGPoint _lastTapPoint;
 
   // The time at which |_lastTapPoint| was most recently set.
@@ skipping 498 matching lines @@
   NOTREACHED();
   return nil;
 }
 
 - (instancetype)initWithCoder:(NSCoder*)aDecoder {
   NOTREACHED();
   return nil;
 }
 
 - (void)dealloc {
-  DCHECK(_isShutdown) << "-shutdown must be called before dealloc.";
+  _tabStripController = nil;
+  _infoBarContainer = nil;
+  _readingListMenuNotifier = nil;
+  if (_bookmarkModel)
+    _bookmarkModel->RemoveObserver(_bookmarkModelBridge.get());
+  [_model removeObserver:self];
+  [[UpgradeCenter sharedInstance] unregisterClient:self];
+  [[NSNotificationCenter defaultCenter] removeObserver:self];
+  [_toolbarController setDelegate:nil];
+  if (_voiceSearchController)
+    _voiceSearchController->SetDelegate(nil);
+  [_rateThisAppDialog setDelegate:nil];
+  [_model closeAllTabs];
 }
 
 #pragma mark - Accessibility
 
 - (BOOL)accessibilityPerformEscape {
   [self dismissPopups];
   return YES;
 }
 
 #pragma mark - Properties
@@ skipping 1245 matching lines @@
   // Delay the cleanup of the unreferenced files received from other apps
   // to not impact startup performance.
   int delay = immediately ? 0 : kExternalFilesCleanupDelaySeconds;
   _externalFileRemover->RemoveAfterDelay(
       base::TimeDelta::FromSeconds(delay),
       base::BindBlockArc(completionHandler ? completionHandler
                                            : ^{
                                              }));
 }
 
-- (void)shutdown {
-  DCHECK(!_isShutdown);
-  _isShutdown = YES;
-
-  _tabStripController = nil;
-  _infoBarContainer = nil;
-  _readingListMenuNotifier = nil;
-  if (_bookmarkModel)
-    _bookmarkModel->RemoveObserver(_bookmarkModelBridge.get());
-  [_model removeObserver:self];
-  [[UpgradeCenter sharedInstance] unregisterClient:self];
-  [[NSNotificationCenter defaultCenter] removeObserver:self];
-  [_toolbarController setDelegate:nil];
-  if (_voiceSearchController)
-    _voiceSearchController->SetDelegate(nil);
-  [_rateThisAppDialog setDelegate:nil];
-  [_model closeAllTabs];
-}
-
 #pragma mark - SnapshotOverlayProvider methods
 
 - (NSArray*)snapshotOverlaysForTab:(Tab*)tab {
   NSMutableArray* overlays = [NSMutableArray array];
   if (![_model webUsageEnabled]) {
     return overlays;
   }
   UIView* voiceSearchView = [self voiceSearchOverlayViewForTab:tab];
   if (voiceSearchView) {
     CGFloat voiceSearchYOffset = [self voiceSearchOverlayYOffsetForTab:tab];
@@ skipping 2946 matching lines @@
 
 - (UIView*)voiceSearchButton {
   return _voiceSearchButton;
 }
 
 - (id<LogoAnimationControllerOwner>)logoAnimationControllerOwner {
   return [self currentLogoAnimationControllerOwner];
 }
 
 @end