Fix crash in StaticHTMLNativeContent when deallocating WKWebView on iOS9

ios/web/web_state/ui/crw_web_controller_container_view.mm

 // Copyright 2015 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/web/web_state/ui/crw_web_controller_container_view.h"
 
 #import "base/ios/weak_nsobject.h"
 #include "base/logging.h"
 #import "base/mac/scoped_nsobject.h"
 #import "ios/web/public/web_state/ui/crw_content_view.h"
@@ skipping 128 matching lines @@
   NOTREACHED();
   return nil;
 }
 
 - (instancetype)initWithFrame:(CGRect)frame {
   NOTREACHED();
   return nil;
 }
 
 - (void)dealloc {
+  if ([_nativeController respondsToSelector:@selector(willBeDismissed)]) {
+    [_nativeController willBeDismissed];

[Eugene But (OOO till 7-30), 2017/01/04 21:24:38]

Calling |willBeDismissed| from dealloc does not seems to be correct either.  How
about calling |[[self scrollView] setDelegate:nil];| from
|StaticHtmlNativeContent dealloc|? Setting delegate to nil twice should not be
an issue.

[Olivier, 2017/01/06 10:03:24]

Done.

+  }
   self.contentViewProxy.contentView = nil;
   [super dealloc];
 }
 
 #pragma mark Accessors
 
 - (CRWWebViewContentView*)webViewContentView {
   return _webViewContentView.get();
 }
 
@@ skipping 179 matching lines @@
   else
     self.toolbarContainerView = nil;
 }
 
 - (void)removeAllToolbars {
   // Resetting the property will remove the toolbars from the hierarchy.
   self.toolbarContainerView = nil;
 }
 
 @end