LabelObserver is no longer retained by the label

ios/chrome/browser/ui/util/label_link_controller.h

 // 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.
 
 #ifndef IOS_CHROME_BROWSER_UI_UTIL_LABEL_LINK_CONTROLLER_H_
 #define IOS_CHROME_BROWSER_UI_UTIL_LABEL_LINK_CONTROLLER_H_
 
 #import <UIKit/UIKit.h>
 #include "ios/chrome/browser/procedural_block_types.h"
 
@@ skipping 27 matching lines @@
 @property(nonatomic, assign) UIColor* linkColor;
 
 // Sets the link underline style for any defined links, updating the controlled
 // label's attributed text accordingly.
 @property(nonatomic, assign) NSUnderlineStyle linkUnderlineStyle;
 
 // Sets the link font for any defined links, updating the controlled label's
 // attributed text accordingly.
 @property(nonatomic, retain) UIFont* linkFont;
 
-// Creates a new controller for |label|, whose lifetime is expected to exceed
-// that of the receiver. |action| is the block called for any tapped link.
+// Creates a new controller for |label|, keeping a strong reference. |action| is
+// the block called for any tapped link.
 - (instancetype)initWithLabel:(UILabel*)label
                        action:(ProceduralBlockWithURL)action;
 
 // Adds a link to the controlled label at |range| in the label's text, which
 // will call the receiver's action block when tapped, passing in |url|.
 - (void)addLinkWithRange:(NSRange)range url:(GURL)url;
 
 @end
 
 @interface LabelLinkController (Testing)
 
 // Testing interface for LabelLinkController.
 
 // This is the class that will be instantiated to do text mapping; by default
 // it is CoreTextMapper, but tests can assign to this property to do dependency
 // injection.
 @property(nonatomic, assign) Class textMapperClass;
 // Returns the tap rects generated by the controller that are associated with
 // |url|.
 - (NSArray*)tapRectsForURL:(GURL)url;
 // Simulates a tap in the controlled label at |point|. No touch events are
 // generated, but |action| should be invoked if |point| is inside a tap rect.
 - (void)tapLabelAtPoint:(CGPoint)point;
 
 @end
 
 #endif  // IOS_CHROME_BROWSER_UI_UTIL_LABEL_LINK_CONTROLLER_H_