LabelObserver is no longer retained by the label

ios/chrome/browser/ui/first_run/welcome_to_chrome_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/chrome/browser/ui/first_run/welcome_to_chrome_view.h"
 
 #include "base/i18n/rtl.h"
 #include "base/logging.h"
 #include "base/strings/sys_string_conversions.h"
 #import "ios/chrome/browser/ui/UIView+SizeClassSupport.h"
 #include "ios/chrome/browser/ui/fancy_ui/primary_action_button.h"
 #include "ios/chrome/browser/ui/first_run/first_run_util.h"
 #include "ios/chrome/browser/ui/ui_util.h"
 #import "ios/chrome/browser/ui/uikit_ui_util.h"
 #import "ios/chrome/browser/ui/util/CRUILabel+AttributeUtils.h"
 #import "ios/chrome/browser/ui/util/label_link_controller.h"
+#import "ios/chrome/browser/ui/util/label_observer.h"
 #include "ios/chrome/common/string_util.h"
 #include "ios/chrome/grit/ios_chromium_strings.h"
 #include "ios/chrome/grit/ios_strings.h"
 #import "ios/third_party/material_roboto_font_loader_ios/src/src/MaterialRobotoFontLoader.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "url/gurl.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
@@ skipping 58 matching lines @@
 // Subview properties are lazily instantiated upon their first use.
 
 // A container view used to layout and center subviews.
 @property(strong, nonatomic, readonly) UIView* containerView;
 // The "Welcome to Chrome" label that appears at the top of the view.
 @property(strong, nonatomic, readonly) UILabel* titleLabel;
 // The Chrome logo image view.
 @property(strong, nonatomic, readonly) UIImageView* imageView;
 // The "Terms of Service" label.
 @property(strong, nonatomic, readonly) UILabel* TOSLabel;
+// Observer for setting the size of the TOSLabel;
+@property(strong, nonatomic) LabelObserver* TOSObserver;
 // The stats reporting opt-in label.
 @property(strong, nonatomic, readonly) UILabel* optInLabel;
+// Observer for setting the size of the optInLabel;
+@property(strong, nonatomic) LabelObserver* optInObserver;
 // The stats reporting opt-in checkbox button.
 @property(strong, nonatomic, readonly) UIButton* checkBoxButton;
 // The "Accept & Continue" button.
 @property(strong, nonatomic, readonly) PrimaryActionButton* OKButton;
 
 // Subview layout methods.  They must be called in the order declared here, as
 // subsequent subview layouts depend on the layouts that precede them.
 - (void)layoutTitleLabel;
 - (void)layoutImageView;
 - (void)layoutTOSLabel;
@@ skipping 21 matching lines @@
 
 // The TOS label button was tapped.
 // TODO(crbug.com/539961): Remove once link detection is fixed.
 - (void)TOSLinkWasTapped;
 
 @end
 
 @implementation WelcomeToChromeView
 
 @synthesize delegate = _delegate;
+@synthesize TOSObserver = _TOSObserver;
+@synthesize optInObserver = _optInObserver;
 
 - (instancetype)initWithFrame:(CGRect)frame {
   self = [super initWithFrame:frame];
   if (self) {
     self.backgroundColor = [UIColor whiteColor];
     self.autoresizingMask =
         UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
   }
   return self;
 }
@@ skipping 24 matching lines @@
                      [weakSelf imageView].frame = finalLogoFrame;
                      [weakSelf titleLabel].alpha = 1.0;
                      [weakSelf TOSLabel].alpha = 1.0;
                      [weakSelf optInLabel].alpha = 1.0;
                      [weakSelf checkBoxButton].alpha = 1.0;
                      [weakSelf OKButton].alpha = 1.0;
                    }
                    completion:nil];
 }
 
+- (void)dealloc {
+  [self.TOSObserver stopObserving];
+  [self.optInObserver stopObserving];
+}
+
 #pragma mark - Accessors
 
 - (BOOL)isCheckBoxSelected {
   return self.checkBoxButton.selected;
 }
 
 - (void)setCheckBoxSelected:(BOOL)checkBoxSelected {
   if (checkBoxSelected != self.checkBoxButton.selected)
     [self checkBoxButtonWasTapped];
 }
@@ skipping 24 matching lines @@
     UIImage* image = [UIImage imageNamed:kAppLogoImageName];
     _imageView = [[UIImageView alloc] initWithImage:image];
     [_imageView setBackgroundColor:[UIColor whiteColor]];
   }
   return _imageView;
 }
 
 - (UILabel*)TOSLabel {
   if (!_TOSLabel) {
     _TOSLabel = [[UILabel alloc] initWithFrame:CGRectZero];
+    self.TOSObserver = [LabelObserver observerForLabel:_TOSLabel];
+    [self.TOSObserver startObserving];

[marq (ping after 24h), 2017/04/19 15:25:19]

What do these observers do? This CL doesn't add any actions to them.

[gambard, 2017/04/19 15:48:18]

The actions are added in CRUILabel+AttributeUtils.h, added here with
_TOSLabel.cr_lineHeight =...
I guess I should add a comment.

[marq (ping after 24h), 2017/04/20 11:52:00]

Yeah, that's non-obvious and kind of clunky.

     [_TOSLabel setNumberOfLines:0];
     [_TOSLabel setTextAlignment:NSTextAlignmentCenter];
   }
   return _TOSLabel;
 }
 
 - (UILabel*)optInLabel {
   if (!_optInLabel) {
     _optInLabel = [[UILabel alloc] initWithFrame:CGRectZero];
+    self.optInObserver = [LabelObserver observerForLabel:_optInLabel];
+    [self.optInObserver startObserving];
     [_optInLabel setNumberOfLines:0];
     [_optInLabel
         setText:l10n_util::GetNSString(IDS_IOS_FIRSTRUN_NEW_OPT_IN_LABEL)];
     [_optInLabel setTextAlignment:NSTextAlignmentNatural];
   }
   return _optInLabel;
 }
 
 - (UIButton*)checkBoxButton {
   if (!_checkBoxButton) {
@@ skipping 279 matching lines @@
 
 - (void)OKButtonWasTapped {
   [self.delegate welcomeToChromeViewDidTapOKButton:self];
 }
 
 - (void)TOSLinkWasTapped {
   [self.delegate welcomeToChromeViewDidTapTOSLink:self];
 }
 
 @end