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

ios/chrome/app/application_delegate/url_opener_unittest.mm

 // Copyright 2016 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 "ios/chrome/app/application_delegate/url_opener.h"
 
 #import <Foundation/Foundation.h>
 
 #include "ios/chrome/app/application_delegate/app_state.h"
 #include "ios/chrome/app/application_delegate/app_state_testing.h"
@@ skipping 59 matching lines @@
 @property(nonatomic, assign) GURL tabURL;
 @property(nonatomic, assign) NSUInteger position;
 @property(nonatomic, assign) ui::PageTransition transition;
 
 - (Tab*)addSelectedTabWithURL:(const GURL&)url
                       atIndex:(NSUInteger)position
                    transition:(ui::PageTransition)transition;
 - (void)expectNewForegroundTab;
 - (void)setActive:(BOOL)active;
 - (TabModel*)tabModel;
-- (void)shutdown;
 @end
 
 @implementation URLOpenerMockBVC
 @synthesize browserState = _browserState;
 @synthesize tabURL = _tabURL;
 @synthesize position = _position;
 @synthesize transition = _transition;
 
 - (Tab*)addSelectedTabWithURL:(const GURL&)url
                       atIndex:(NSUInteger)position
@@ skipping 13 matching lines @@
 }
 
 - (void)setPrimary:(BOOL)primary {
   // no-op
 }
 
 - (TabModel*)tabModel {
   return nil;
 }
 
-- (void)shutdown {
-  // no-op
-}
-
 @end
 
 class URLOpenerTest : public PlatformTest {
  protected:
-  void TearDown() override {
-    [main_controller_ stopChromeMain];
-    PlatformTest::TearDown();
-  }
-
   MainController* GetMainController() {
     if (!main_controller_) {
       main_controller_ = [[MainController alloc] init];
       [main_controller_ setUpAsForegrounded];
       id mainTabModel = [OCMockObject mockForClass:[TabModel class]];
       [[mainTabModel stub] resetSessionMetrics];
       [[mainTabModel stub] browserStateDestroyed];
       [[mainTabModel stub] addObserver:[OCMArg any]];
       [[mainTabModel stub] removeObserver:[OCMArg any]];
       [[main_controller_ browserViewInformation] setMainTabModel:mainTabModel];
@@ skipping 347 matching lines @@
   [URLOpener handleLaunchOptions:launchOptions
                applicationActive:NO
                        tabOpener:tabOpenerMock
               startupInformation:startupInformationMock
                         appState:appStateMock];
 
   // Test.
   EXPECT_TRUE(hasBeenCalled);
   EXPECT_OCMOCK_VERIFY(startupInformationMock);
 }