[iOS] Break retain cycle in InfoBars.

ios/chrome/browser/passwords/update_password_infobar_controller.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.
 
 #import "ios/chrome/browser/passwords/update_password_infobar_controller.h"
 
+#include "base/ios/weak_nsobject.h"
 #import "base/mac/objc_property_releaser.h"
 #include "base/strings/string_util.h"
 #include "base/strings/sys_string_conversions.h"
 #include "ios/chrome/browser/infobars/confirm_infobar_controller+protected.h"
 #include "ios/chrome/browser/passwords/ios_chrome_update_password_infobar_delegate.h"
 #import "ios/chrome/browser/ui/elements/selector_coordinator.h"
 #import "ios/chrome/browser/ui/infobars/infobar_view.h"
 
 namespace {
 // Tag for the account link in the info bar message. Set to 10 to avoid conflict
@@ skipping 37 matching lines @@
   // If there are multiple possible credentials, turn the account string into a
   // link.
   if (_delegate->ShowMultipleAccounts()) {
     base::string16 usernameLink = base::SysNSStringToUTF16([[view class]
         stringAsLink:base::SysUTF16ToNSString(_delegate->selected_account())
                  tag:kAccountTag]);
     base::ReplaceFirstSubstringAfterOffset(
         &messageText, 0, _delegate->selected_account(), usernameLink);
   }
 
+  base::WeakNSObject<UpdatePasswordInfoBarController> weakSelf(self);
   [view addLabel:base::SysUTF16ToNSString(messageText)
           action:^(NSUInteger tag) {
-            [self infobarLinkDidPress:tag];
+            [weakSelf infobarLinkDidPress:tag];
           }];
 }
 
 - (void)infobarLinkDidPress:(NSUInteger)tag {
   [super infobarLinkDidPress:tag];
   if (tag != kAccountTag)
     return;
 
   UIViewController* baseViewController =
       [[UIApplication sharedApplication] keyWindow].rootViewController;
   self.selectorCoordinator = [[[SelectorCoordinator alloc]
       initWithBaseViewController:baseViewController] autorelease];
   self.selectorCoordinator.delegate = self;
   self.selectorCoordinator.options =
       [NSOrderedSet orderedSetWithArray:_delegate->GetAccounts()];
   self.selectorCoordinator.defaultOption =
       base::SysUTF16ToNSString(_delegate->selected_account());
   [self.selectorCoordinator start];
 }
 
 #pragma mark SelectorCoordinatorDelegate
 
 - (void)selectorCoordinator:(SelectorCoordinator*)coordinator
     didCompleteWithSelection:(NSString*)selection {
   _delegate->set_selected_account(base::SysNSStringToUTF16(selection));
   [self updateInfobarLabel:self.view];
 }
 
 @end