[iOS] Improve readability of UserSigninViewController.

It was difficult to understand the current constraint layout of the
"Turn on Sync" page due to the inconsistencies in the view manipulation.
This patch attempts to make the layout and styling of the views and
buttons more straightforward.

Bug: 1105853
Change-Id: I0c0bca5aa1be5200d3be414804976efc8ed7ef22
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2312556
Commit-Queue: Nohemi Fernandez <fernandex@chromium.org>
Reviewed-by: Jérôme Lebel <jlebel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791778}

ios/chrome/browser/ui/authentication/signin/user_signin/user_signin_coordinator.mm

@@ -219,7 +219,7 @@ const CGFloat kFadeOutAnimationDuration = 0.16f;
 - (void)unifiedConsentCoordinatorNeedPrimaryButtonUpdate:
     (UnifiedConsentCoordinator*)coordinator {
   DCHECK_EQ(self.unifiedConsentCoordinator, coordinator);
-  [self.viewController updatePrimaryButtonStyle];
+  [self.viewController setConfirmationButtonProperties];
 }
 
 #pragma mark - UserSigninViewControllerDelegate
@@ -330,7 +330,7 @@ const CGFloat kFadeOutAnimationDuration = 0.16f;
   [self.unifiedConsentCoordinator resetSettingLinkTapped];
   self.unifiedConsentCoordinator.uiDisabled = NO;
   [self.viewController signinDidStop];
-  [self.viewController updatePrimaryButtonStyle];
+  [self.viewController setConfirmationButtonProperties];
 }
 
 #pragma mark - Private

ios/chrome/browser/ui/authentication/signin/user_signin/user_signin_view_controller.h

@@ -48,8 +48,10 @@
 // of the screen.
 - (void)markUnifiedConsentScreenReachedBottom;
 
-// Updates the primary button based on the user sign-in state.
-- (void)updatePrimaryButtonStyle;
+// Sets the title, styling, and other button properties for the confirmation
+// button based on the user consent text that is currently displayed on-screen
+// and the whether the user has previously been signed-in.
+- (void)setConfirmationButtonProperties;
 
 // Returns the supported orientations for the device type:
 // |UIInterfaceOrientationPortrait| orientation on iPhone and all other

ios/chrome/browser/ui/authentication/signin/user_signin/user_signin_view_controller.mm

@@ -113,23 +113,25 @@ enum AuthenticationButtonType {
   // This is the first time the unified consent screen has reached the bottom.
   if (self.hasUnifiedConsentScreenReachedBottom == NO) {
     self.hasUnifiedConsentScreenReachedBottom = YES;
-    [self updatePrimaryButtonStyle];
+    [self setConfirmationButtonProperties];
   }
 }
 
-- (void)updatePrimaryButtonStyle {
+- (void)setConfirmationButtonProperties {
   if (![self.delegate unifiedConsentCoordinatorHasIdentity]) {
     // User has not added an account. Display 'add account' button.
     [self.confirmationButton setTitle:self.addAccountButtonTitle
                              forState:UIControlStateNormal];
-    [self setConfirmationStylingWithButton:self.confirmationButton];
+    [self setBlueBackgroundStylingWithButton:self.confirmationButton];
     self.confirmationButton.tag = AuthenticationButtonTypeAddAccount;
     self.confirmationButton.accessibilityIdentifier =
         kAddAccountAccessibilityIdentifier;
   } else if (!self.hasUnifiedConsentScreenReachedBottom) {
     // User has not scrolled to the bottom of the user consent screen.
     // Display 'more' button.
-    [self updateButtonAsMoreButton:self.confirmationButton];
+    [self.confirmationButton setTitle:self.scrollButtonTitle
+                             forState:UIControlStateNormal];
+    [self setMoreButtonStylingWithButton:self.confirmationButton];
     self.confirmationButton.tag = AuthenticationButtonTypeMore;
     self.confirmationButton.accessibilityIdentifier =
         kMoreAccessibilityIdentifier;
@@ -137,7 +139,7 @@ enum AuthenticationButtonType {
     // By default display 'Yes I'm in' button.
     [self.confirmationButton setTitle:self.confirmationButtonTitle
                              forState:UIControlStateNormal];
-    [self setConfirmationStylingWithButton:self.confirmationButton];
+    [self setBlueBackgroundStylingWithButton:self.confirmationButton];
     self.confirmationButton.tag = AuthenticationButtonTypeConfirmation;
     self.confirmationButton.accessibilityIdentifier =
         kConfirmationAccessibilityIdentifier;
@@ -191,23 +193,41 @@ enum AuthenticationButtonType {
   [super viewDidLoad];
   self.view.backgroundColor = self.systemBackgroundColor;
 
-  [self addConfirmationButton];
-  [self addSkipSigninButton];
-  [self embedUserConsentView];
+  self.containerView = [[UIView alloc] init];
+  self.containerView.translatesAutoresizingMaskIntoConstraints = NO;
+  [self.view addSubview:self.containerView];
+
+  self.confirmationButton = [[UIButton alloc] init];
+  [self setConfirmationButtonProperties];
+  [self maybeEnablePointerSupportWithButton:self.confirmationButton];
+  self.confirmationButton.translatesAutoresizingMaskIntoConstraints = NO;
+  [self.view addSubview:self.confirmationButton];
+
+  self.skipSigninButton = [[UIButton alloc] init];
+  [self setSkipSigninButtonProperties];
+  [self maybeEnablePointerSupportWithButton:self.skipSigninButton];
+  self.skipSigninButton.translatesAutoresizingMaskIntoConstraints = NO;
+  [self.view addSubview:self.skipSigninButton];
+
+  self.unifiedConsentViewController.view
+      .translatesAutoresizingMaskIntoConstraints = NO;
+  [self addChildViewController:self.unifiedConsentViewController];
+  [self.containerView addSubview:self.unifiedConsentViewController.view];
+  [self.unifiedConsentViewController didMoveToParentViewController:self];
+
+  self.gradientView.translatesAutoresizingMaskIntoConstraints = NO;
+  [self.containerView addSubview:self.gradientView];
 
   [NSLayoutConstraint activateConstraints:@[
-    // Contraints for the container view. The bottom constraint has to be set
-    // according to the size class.
+    // Note that the bottom constraint of the container view and
+    // |unifiedConsentViewController.view| is dependent on the selected
+    // Accessibility options in Settings, e.g. text size. These constraints
+    // are computed in |setAccessibilityLayoutConstraints|.
     [self.containerView.topAnchor constraintEqualToAnchor:self.view.topAnchor],
     [self.containerView.leadingAnchor
         constraintEqualToAnchor:self.view.leadingAnchor],
     [self.containerView.trailingAnchor
         constraintEqualToAnchor:self.view.trailingAnchor],
-  ]];
-
-  [self.containerView addSubview:self.gradientView];
-  self.gradientView.translatesAutoresizingMaskIntoConstraints = NO;
-  [NSLayoutConstraint activateConstraints:@[
     // The gradient view needs to be attatched to the bottom of the user
     // consent view which contains the scroll view.
     [self.gradientView.bottomAnchor
@@ -222,12 +242,12 @@ enum AuthenticationButtonType {
     [self.gradientView.heightAnchor constraintEqualToConstant:kGradientHeight],
   ]];
 
-  [self updateViewsAndConstraints];
+  [self setAccessibilityLayoutConstraints];
 }
 
 - (void)viewDidLayoutSubviews {
   [super viewDidLayoutSubviews];
-  [self updateViewsAndConstraints];
+  [self setAccessibilityLayoutConstraints];
 }
 
 #pragma mark - Constraints
@@ -257,8 +277,9 @@ enum AuthenticationButtonType {
   return constraints;
 }
 
-// Updates view sizes and constraints.
-- (void)updateViewsAndConstraints {
+// Sets the layout constraints depending on the selected text size in the
+// accessibility Settings.
+- (void)setAccessibilityLayoutConstraints {
   BOOL isRegularSizeClass = IsRegularXRegularSizeClass(self.traitCollection);
   UIFontTextStyle fontStyle;
   if (isRegularSizeClass) {
@@ -406,82 +427,38 @@ enum AuthenticationButtonType {
   AddSameCenterConstraints(self.confirmationButton, self.activityIndicator);
 }
 
-// Embeds the user consent view in the root view.
-- (void)embedUserConsentView {
-  DCHECK(self.confirmationButton);
-  DCHECK(self.unifiedConsentViewController);
-  self.unifiedConsentViewController.view
-      .translatesAutoresizingMaskIntoConstraints = NO;
-
-  self.containerView = [[UIView alloc] init];
-  self.containerView.translatesAutoresizingMaskIntoConstraints = NO;
-  [self.view addSubview:self.containerView];
-  [self addChildViewController:self.unifiedConsentViewController];
-  [self.containerView addSubview:self.unifiedConsentViewController.view];
-  [self.unifiedConsentViewController didMoveToParentViewController:self];
-}
-
-// Sets up confirmation button properties and adds it to the user sign-in view.
-- (void)addConfirmationButton {
-  DCHECK(self.unifiedConsentViewController);
-  self.confirmationButton = [[UIButton alloc] init];
-#if defined(__IPHONE_13_4)
-  if (@available(iOS 13.4, *)) {
-    if (base::FeatureList::IsEnabled(kPointerSupport)) {
-      self.confirmationButton.pointerInteractionEnabled = YES;
-      // This button can either have an opaque background (i.e., "Add Account"
-      // or "Yes, I'm in!") or a transparent background (i.e., "More") when
-      // scrolling is needed to reach the bottom of the screen.
-      self.confirmationButton.pointerStyleProvider =
-          CreateOpaqueOrTransparentButtonPointerStyleProvider();
-    }
-  }
-#endif  // defined(__IPHONE_13_4)
-
-  [self addSubviewWithButton:self.confirmationButton];
-  // Note that the button style will depend on the user sign-in state.
-  [self updatePrimaryButtonStyle];
-}
-
-// Sets up skip sign-in button properties and adds it to the user sign-in view.
-- (void)addSkipSigninButton {
-  DCHECK(!self.skipSigninButton);
-  DCHECK(self.unifiedConsentViewController);
-  self.skipSigninButton = [[UIButton alloc] init];
+// Sets the text, styling, and other button properties for the skip sign-in
+// button.
+- (void)setSkipSigninButtonProperties {
+  DCHECK(self.skipSigninButton);
   self.skipSigninButton.accessibilityIdentifier =
       kSkipSigninAccessibilityIdentifier;
-  [self addSubviewWithButton:self.skipSigninButton];
   [self.skipSigninButton setTitle:self.skipSigninButtonTitle
                          forState:UIControlStateNormal];
-  [self setSkipSigninStylingWithButton:self.skipSigninButton];
+  [self.skipSigninButton setTitleColor:[UIColor colorNamed:kBlueColor]
+                              forState:UIControlStateNormal];
   [self.skipSigninButton addTarget:self
                             action:@selector(onSkipSigninButtonPressed:)
                   forControlEvents:UIControlEventTouchUpInside];
+}
+
+#pragma mark - Styling
+
+// Enables pointer support for the button if it is supported on the iOS version.
+- (void)maybeEnablePointerSupportWithButton:(UIButton*)button {
+  DCHECK(button);
 #if defined(__IPHONE_13_4)
   if (@available(iOS 13.4, *)) {
     if (base::FeatureList::IsEnabled(kPointerSupport)) {
-      self.skipSigninButton.pointerInteractionEnabled = YES;
-      self.skipSigninButton.pointerStyleProvider =
+      button.pointerInteractionEnabled = YES;
+      button.pointerStyleProvider =
           CreateTransparentButtonPointerStyleProvider();
     }
   }
 #endif  // defined(__IPHONE_13_4)
 }
 
-// Sets up button properties and adds it to view.
-- (void)addSubviewWithButton:(UIButton*)button {
-  [button
-      setContentCompressionResistancePriority:UILayoutPriorityRequired
-                                      forAxis:UILayoutConstraintAxisVertical];
-  [button setContentHuggingPriority:UILayoutPriorityRequired
-                            forAxis:UILayoutConstraintAxisVertical];
-  [self.view addSubview:button];
-  button.translatesAutoresizingMaskIntoConstraints = NO;
-}
-
-#pragma mark - Styling
-
-- (void)setConfirmationStylingWithButton:(UIButton*)button {
+- (void)setBlueBackgroundStylingWithButton:(UIButton*)button {
   DCHECK(button);
   button.backgroundColor = [UIColor colorNamed:kBlueColor];
   button.layer.cornerRadius = kButtonCornerRadius;
@@ -490,18 +467,13 @@ enum AuthenticationButtonType {
   [button setImage:nil forState:UIControlStateNormal];
 }
 
-- (void)setSkipSigninStylingWithButton:(UIButton*)button {
+- (void)setMoreButtonStylingWithButton:(UIButton*)button {
   DCHECK(button);
-  [button setTitleColor:[UIColor colorNamed:kBlueColor]
-               forState:UIControlStateNormal];
-}
-
-- (void)updateButtonAsMoreButton:(UIButton*)button {
-  [button setTitle:self.scrollButtonTitle forState:UIControlStateNormal];
   UIImage* buttonImage = [[UIImage imageNamed:@"signin_confirmation_more"]
       imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate];
   [button setImage:buttonImage forState:UIControlStateNormal];
-  [self setSkipSigninStylingWithButton:button];
+  [button setTitleColor:[UIColor colorNamed:kBlueColor]
+               forState:UIControlStateNormal];
   if (UIApplication.sharedApplication.userInterfaceLayoutDirection ==
       UIUserInterfaceLayoutDirectionLeftToRight) {
     button.imageEdgeInsets = UIEdgeInsetsMake(0, -kImageInset, 0, 0);