[iOS] Support Accessibility ContentSize on NTP header

This CL changes the header of the "Articles for you" section of the NTP
to have a better support for the "accessibility" categories of preferred
content size chosen by the user.

Bug: 893524
Cq-Include-Trybots: luci.chromium.try:ios-simulator-cronet;luci.chromium.try:ios-simulator-full-configs
Change-Id: I56ed6f89e7767697083c3e8e5d5a796db3066aee
Reviewed-on: https://chromium-review.googlesource.com/c/1273522
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599145}

ios/chrome/browser/ui/content_suggestions/cells/content_suggestions_articles_header_item.mm

@@ -70,6 +70,14 @@ const int kLabelColorRGB = 0x6D6D72;
 
 #pragma mark - ContentSuggestionsArticlesHeaderCell
 
+@interface ContentSuggestionsArticlesHeaderCell ()
+
+@property(nonatomic, strong) NSArray<NSLayoutConstraint*>* standardConstraints;
+@property(nonatomic, strong)
+    NSArray<NSLayoutConstraint*>* accessibilityConstraints;
+
+@end
+
 @implementation ContentSuggestionsArticlesHeaderCell
 
 @synthesize button = _button;
@@ -83,34 +91,62 @@ const int kLabelColorRGB = 0x6D6D72;
     _label.translatesAutoresizingMaskIntoConstraints = NO;
     _label.font = [UIFont preferredFontForTextStyle:UIFontTextStyleFootnote];
     _label.textColor = UIColorFromRGB(kLabelColorRGB, 1.0);
+    _label.adjustsFontForContentSizeCategory = YES;
     _label.adjustsFontSizeToFitWidth = YES;
 
     _button = [UIButton buttonWithType:UIButtonTypeSystem];
     _button.translatesAutoresizingMaskIntoConstraints = NO;
     _button.titleLabel.font =
         [UIFont preferredFontForTextStyle:UIFontTextStyleFootnote];
+    _button.titleLabel.adjustsFontForContentSizeCategory = YES;
     [_button addTarget:self
                   action:@selector(buttonTapped)
         forControlEvents:UIControlEventTouchUpInside];
 
     [self.contentView addSubview:_button];
     [self.contentView addSubview:_label];
-    [NSLayoutConstraint activateConstraints:@[
-      [_label.leadingAnchor
-          constraintEqualToAnchor:self.contentView.leadingAnchor
-                         constant:kTextMargin],
-      [_label.topAnchor constraintEqualToAnchor:self.contentView.topAnchor],
+
+    _standardConstraints = @[
       [_label.bottomAnchor
           constraintEqualToAnchor:self.contentView.bottomAnchor],
+      [_button.topAnchor constraintEqualToAnchor:self.contentView.topAnchor],
+      [_label.trailingAnchor
+          constraintLessThanOrEqualToAnchor:_button.leadingAnchor],
       [_button.trailingAnchor
           constraintEqualToAnchor:self.contentView.trailingAnchor
                          constant:-kTextMargin],
-      [_button.topAnchor constraintEqualToAnchor:self.contentView.topAnchor],
+    ];
+    _accessibilityConstraints = @[
+      [_label.bottomAnchor
+          constraintEqualToAnchor:self.contentView.centerYAnchor],
+      [_button.topAnchor
+          constraintEqualToAnchor:self.contentView.centerYAnchor],
+      [_label.trailingAnchor
+          constraintLessThanOrEqualToAnchor:self.contentView.trailingAnchor
+                                   constant:-kTextMargin],
+      [_button.leadingAnchor
+          constraintEqualToAnchor:self.contentView.leadingAnchor
+                         constant:kTextMargin],
+      [_button.trailingAnchor
+          constraintLessThanOrEqualToAnchor:self.contentView.trailingAnchor
+                                   constant:-kTextMargin],
+    ];
+
+    [NSLayoutConstraint activateConstraints:@[
+      [_label.leadingAnchor
+          constraintEqualToAnchor:self.contentView.leadingAnchor
+                         constant:kTextMargin],
+      [_label.topAnchor constraintEqualToAnchor:self.contentView.topAnchor],
       [_button.bottomAnchor
           constraintEqualToAnchor:self.contentView.bottomAnchor],
-      [_label.trailingAnchor
-          constraintLessThanOrEqualToAnchor:_button.leadingAnchor]
     ]];
+
+    if (ContentSizeCategoryIsAccessibilityCategory(
+            self.traitCollection.preferredContentSizeCategory)) {
+      [NSLayoutConstraint activateConstraints:_accessibilityConstraints];
+    } else {
+      [NSLayoutConstraint activateConstraints:_standardConstraints];
+    }
   }
   return self;
 }
@@ -120,6 +156,27 @@ const int kLabelColorRGB = 0x6D6D72;
   self.delegate = nil;
 }
 
+#pragma mark - UIView
+
+- (void)traitCollectionDidChange:(UITraitCollection*)previousTraitCollection {
+  [super traitCollectionDidChange:previousTraitCollection];
+  BOOL isCurrentCategoryAccessibility =
+      ContentSizeCategoryIsAccessibilityCategory(
+          self.traitCollection.preferredContentSizeCategory);
+  BOOL isPreviousCategoryAccessibility =
+      ContentSizeCategoryIsAccessibilityCategory(
+          previousTraitCollection.preferredContentSizeCategory);
+  if (isCurrentCategoryAccessibility != isPreviousCategoryAccessibility) {
+    if (isCurrentCategoryAccessibility) {
+      [NSLayoutConstraint deactivateConstraints:self.standardConstraints];
+      [NSLayoutConstraint activateConstraints:self.accessibilityConstraints];
+    } else {
+      [NSLayoutConstraint deactivateConstraints:self.accessibilityConstraints];
+      [NSLayoutConstraint activateConstraints:self.standardConstraints];
+    }
+  }
+}
+
 #pragma mark Private
 
 // Callback for the button action.

ios/chrome/browser/ui/content_suggestions/content_suggestions_view_controller.mm

@@ -439,9 +439,16 @@ const CGFloat kCardBorderRadius = 11;
   if ([self.collectionUpdater isHeaderSection:section]) {
     return CGSizeMake(0, [self.headerSynchronizer headerHeight]);
   }
-  return [super collectionView:collectionView
-                               layout:collectionViewLayout
-      referenceSizeForHeaderInSection:section];
+  CGSize defaultSize = [super collectionView:collectionView
+                                      layout:collectionViewLayout
+             referenceSizeForHeaderInSection:section];
+  if (ContentSizeCategoryIsAccessibilityCategory(
+          self.traitCollection.preferredContentSizeCategory) &&
+      [self.collectionUpdater isContentSuggestionsSection:section]) {
+    // Double the size of the header as it is now on two lines.
+    defaultSize.height *= 2;
+  }
+  return defaultSize;
 }
 
 - (BOOL)collectionView:(nonnull UICollectionView*)collectionView