[ios] WebStateList owns all WebState it manages.

ios/chrome/browser/ui/fullscreen_controller.mm

 // Copyright 2013 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/fullscreen_controller.h"
 
 #include <cmath>
 
 #include "base/logging.h"
 #include "base/mac/objc_property_releaser.h"
@@ skipping 695 matching lines @@
 
 - (void)pageLoaded:(CRWWebController*)webController {
   [self enableFullScreen];
   web::WebState* webState = webController.webState;
   if (webState) {
     BOOL MIMETypeIsPDF = webState->GetContentsMimeType() == "application/pdf";
     [webViewProxy_ setShouldUseInsetForTopPadding:MIMETypeIsPDF];
   }
 }
 
-- (void)webControllerWillClose:(CRWWebController*)webController {
-  [webController removeObserver:self];
-}
-
 #pragma mark -
 #pragma mark CRWWebViewScrollViewObserver
 
 - (void)webViewScrollViewDidScroll:
     (CRWWebViewScrollViewProxy*)webViewScrollViewProxy {
   CGFloat previousRequestedContentOffset =
       webViewScrollViewProxy.contentOffset.y;
   if ([self shouldIgnoreScroll:webViewScrollViewProxy]) {
     // Do not act on those events, just record the eventual move.
     self.previousContentOffset = previousRequestedContentOffset;
@@ skipping 87 matching lines @@
   overscrollActionsInProgress_ = NO;
 }
 
 #pragma mark - Used for testing
 
 + (void)setEnabledForTests:(BOOL)enabled {
   gEnabledForTests = enabled;
 }
 
 @end