[iOS] Break retain cycle in InfoBars.

ios/chrome/browser/infobars/confirm_infobar_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/infobars/confirm_infobar_controller.h"
 
 #include "base/mac/foundation_util.h"
 #include "base/strings/string_util.h"
 #include "base/strings/sys_string_conversions.h"
 #include "components/infobars/core/confirm_infobar_delegate.h"
@@ skipping 100 matching lines @@
     return;
   if (_confirmInfobarDelegate->GetLinkText().length()) {
     base::string16 msgLink = base::SysNSStringToUTF16([[view class]
         stringAsLink:base::SysUTF16ToNSString(
                          _confirmInfobarDelegate->GetLinkText())
                  tag:ConfirmInfoBarUITags::TITLE_LINK]);
     base::string16 messageText = _confirmInfobarDelegate->GetMessageText();
     base::ReplaceFirstSubstringAfterOffset(
         &messageText, 0, _confirmInfobarDelegate->GetLinkText(), msgLink);
 
+    __weak ConfirmInfoBarController* weakSelf = self;
     [view addLabel:base::SysUTF16ToNSString(messageText)
             action:^(NSUInteger tag) {
-              [self infobarLinkDidPress:tag];
+              [weakSelf infobarLinkDidPress:tag];
             }];
   } else {
     NSString* label =
         base::SysUTF16ToNSString(_confirmInfobarDelegate->GetMessageText());
     [view addLabel:label];
   }
 }
 
 #pragma mark - Handling of User Events
 
@@ skipping 18 matching lines @@
   if (!self.delegate) {
     return;
   }
   if (tag == ConfirmInfoBarUITags::TITLE_LINK) {
     _confirmInfobarDelegate->LinkClicked(
         WindowOpenDisposition::NEW_FOREGROUND_TAB);
   }
 }
 
 @end