[iOS] Break retain cycle in InfoBars.

This CLs breaks retain cycles such as:
InfoBarView -> LabelLinkController ->
BeforeTranslateInfoBarController -> InfoBarView

BUG=732384

Review-Url: https://codereview.chromium.org/2933833002
Cr-Commit-Position: refs/heads/master@{#478618}

ios/chrome/browser/infobars/confirm_infobar_controller.mm

@@ -118,9 +118,10 @@ ConfirmInfoBarDelegate::InfoBarButton UITagToButton(NSUInteger tag) {
     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 =

ios/chrome/browser/passwords/update_password_infobar_controller.mm

@@ -4,6 +4,7 @@
 
 #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"
@@ -61,9 +62,10 @@ NSUInteger kAccountTag = 10;
         &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];
           }];
 }
 

ios/chrome/browser/translate/before_translate_infobar_controller.mm

@@ -7,6 +7,7 @@
 #include <stddef.h>
 #import <UIKit/UIKit.h>
 
+#include "base/ios/weak_nsobject.h"
 #include "base/logging.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/strings/sys_string_conversions.h"
@@ -172,9 +173,11 @@ NSTimeInterval kPickerAnimationDurationInSeconds = 0.2;
   NSString* label =
       l10n_util::GetNSStringF(IDS_TRANSLATE_INFOBAR_BEFORE_MESSAGE_IOS,
                               originalLanguageWithLink, targetLanguageWithLink);
+
+  base::WeakNSObject<BeforeTranslateInfoBarController> weakSelf(self);
   [view addLabel:label
           action:^(NSUInteger tag) {
-            [self infobarLinkDidPress:tag];
+            [weakSelf infobarLinkDidPress:tag];
           }];
 }