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

ios/chrome/browser/ui/main/browser_view_wrangler.mm

Index: ios/chrome/browser/ui/main/browser_view_wrangler.mm
diff --git a/ios/chrome/browser/ui/main/browser_view_wrangler.mm b/ios/chrome/browser/ui/main/browser_view_wrangler.mm
index d31d546cd74eaa125df7ca7f5f044b9aef29fa3c..ef7f08f6cb859cc94b6d03c6cb2c943e61f2529f 100644
--- a/ios/chrome/browser/ui/main/browser_view_wrangler.mm
+++ b/ios/chrome/browser/ui/main/browser_view_wrangler.mm
@@ -27,7 +27,6 @@
 @interface BrowserViewWrangler ()<TabModelObserver> {
   ios::ChromeBrowserState* _browserState;
   __unsafe_unretained id<TabModelObserver> _tabModelObserver;
-  BOOL _isShutdown;
 
   base::mac::ObjCPropertyReleaser _propertyReleaser_BrowserViewWrangler;
 }
@@ -83,7 +82,25 @@
 }
 
 - (void)dealloc {
-  DCHECK(_isShutdown) << "-shutdown must be called before -dealloc";
+  if (_tabModelObserver) {
+    [_mainTabModel removeObserver:_tabModelObserver];
+    [_otrTabModel removeObserver:_tabModelObserver];
+  }
+  [_mainTabModel removeObserver:self];
+  [_otrTabModel removeObserver:self];
+
+  // Stop URL monitoring of the main tab model.
+  ios_internal::breakpad::StopMonitoringURLsForTabModel(_mainTabModel);
+
+  // Stop Breakpad state monitoring of both tab models (if necessary).
+  ios_internal::breakpad::StopMonitoringTabStateForTabModel(_mainTabModel);
+  ios_internal::breakpad::StopMonitoringTabStateForTabModel(_otrTabModel);
+
+  // Normally other objects will take care of unhooking the tab models from
+  // the browser state, but this code should ensure that it happens regardless.
+  [_mainTabModel browserStateDestroyed];
+  [_otrTabModel browserStateDestroyed];
+
   [super dealloc];
 }
 
@@ -266,39 +283,6 @@
   }
 }
 
-- (void)shutdown {
-  DCHECK(!_isShutdown);
-  _isShutdown = YES;
-
-  if (_tabModelObserver) {
-    [_mainTabModel removeObserver:_tabModelObserver];
-    [_otrTabModel removeObserver:_tabModelObserver];
-    _tabModelObserver = nil;
-  }
-
-  [_mainTabModel removeObserver:self];
-  [_otrTabModel removeObserver:self];
-
-  // Stop URL monitoring of the main tab model.
-  ios_internal::breakpad::StopMonitoringURLsForTabModel(_mainTabModel);
-
-  // Stop Breakpad state monitoring of both tab models (if necessary).
-  ios_internal::breakpad::StopMonitoringTabStateForTabModel(_mainTabModel);
-  ios_internal::breakpad::StopMonitoringTabStateForTabModel(_otrTabModel);
-
-  // Normally other objects will take care of unhooking the tab models from
-  // the browser state, but this code should ensure that it happens regardless.
-  [_mainTabModel browserStateDestroyed];
-  [_otrTabModel browserStateDestroyed];
-
-  [_mainBVC shutdown];
-  [_otrBVC shutdown];
-  self.mainBVC = nil;
-  self.otrBVC = nil;
-
-  _browserState = nullptr;
-}
-
 #pragma mark - Internal methods
 
 - (TabModel*)buildOtrTabModel:(BOOL)empty {