[AF][IOS] Fixes the GooglePay logo animation in the FormSuggestionView

After crrev.com/c/1078871 that updated FormSuggestionView and
FormSuggestionLabel to use AutoLayout, the Google Pay logo stopped
animating. This CL fixes that regression and also changes the code
slightly so that the subviews are more lazily created.

Bug: 852890
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I5388a3c4a7df2819e14b5772368e07f16c98564e
Reviewed-on: https://chromium-review.googlesource.com/1101543
Commit-Queue: Moe Ahmadi <mahmadi@chromium.org>
Reviewed-by: Vasilii Sukhanov <vasilii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567997}

ios/chrome/browser/autofill/form_suggestion_view.mm

@@ -28,9 +28,19 @@ const CGFloat kSuggestionHorizontalMargin = 6;
 
 }  // namespace
 
+@interface FormSuggestionView ()
+
+// Creates and adds subviews.
+- (void)setupSubviews;
+
+@end
+
 @implementation FormSuggestionView {
   // The FormSuggestions that are displayed by this view.
   NSArray* _suggestions;
+
+  // Handles user interactions.
+  id<FormSuggestionViewClient> _client;
 }
 
 - (instancetype)initWithFrame:(CGRect)frame
@@ -38,8 +48,25 @@ const CGFloat kSuggestionHorizontalMargin = 6;
                   suggestions:(NSArray*)suggestions {
   self = [super initWithFrame:frame];
   if (self) {
+    _client = client;
     _suggestions = [suggestions copy];
+  }
+  return self;
+}
 
+#pragma mark - UIView
+
+- (void)willMoveToSuperview:(UIView*)newSuperview {
+  // Create and add subviews the first time this moves to a superview.
+  if (newSuperview && self.subviews.count == 0) {
+    [self setupSubviews];
+  }
+  [super willMoveToSuperview:newSuperview];
+}
+
+#pragma mark - Helper methods
+
+- (void)setupSubviews {
   self.showsVerticalScrollIndicator = NO;
   self.showsHorizontalScrollIndicator = NO;
   self.bounces = NO;
@@ -48,42 +75,36 @@ const CGFloat kSuggestionHorizontalMargin = 6;
   UIStackView* stackView = [[UIStackView alloc] initWithArrangedSubviews:@[]];
   stackView.axis = UILayoutConstraintAxisHorizontal;
   stackView.layoutMarginsRelativeArrangement = YES;
-    stackView.layoutMargins = UIEdgeInsetsMake(
-        kSuggestionVerticalMargin, kSuggestionHorizontalMargin,
+  stackView.layoutMargins =
+      UIEdgeInsetsMake(kSuggestionVerticalMargin, kSuggestionHorizontalMargin,
                        kSuggestionVerticalMargin, kSuggestionHorizontalMargin);
   stackView.spacing = kSuggestionHorizontalMargin;
   stackView.translatesAutoresizingMaskIntoConstraints = NO;
   [self addSubview:stackView];
+  AddSameConstraints(stackView, self);
+  [stackView.heightAnchor constraintEqualToAnchor:self.heightAnchor].active =
+      true;
 
-    void (^setupBlock)(FormSuggestion* suggestion, NSUInteger idx, BOOL* stop) =
-        ^(FormSuggestion* suggestion, NSUInteger idx, BOOL* stop) {
+  auto setupBlock = ^(FormSuggestion* suggestion, NSUInteger idx, BOOL* stop) {
+    // Disable user interaction with suggestion if it is Google Pay logo.
     BOOL userInteractionEnabled =
-              suggestion.identifier !=
-              autofill::POPUP_ITEM_ID_GOOGLE_PAY_BRANDING;
-          UIView* label = [[FormSuggestionLabel alloc]
-                  initWithSuggestion:suggestion
+        suggestion.identifier != autofill::POPUP_ITEM_ID_GOOGLE_PAY_BRANDING;
+
+    UIView* label =
+        [[FormSuggestionLabel alloc] initWithSuggestion:suggestion
                                                   index:idx
                                  userInteractionEnabled:userInteractionEnabled
                                          numSuggestions:[_suggestions count]
-                              client:client];
+                                                 client:_client];
     [stackView addArrangedSubview:label];
-        };
-    [_suggestions enumerateObjectsUsingBlock:setupBlock];
-    AddSameConstraints(stackView, self);
-    [stackView.heightAnchor constraintEqualToAnchor:self.heightAnchor].active =
-        true;
-  }
-  return self;
-}
 
-- (void)willMoveToSuperview:(UIView*)newSuperview {
-  FormSuggestion* firstSuggestion = [_suggestions firstObject];
-  if (firstSuggestion.identifier ==
-      autofill::POPUP_ITEM_ID_GOOGLE_PAY_BRANDING) {
-    UIView* firstLabel = [self.subviews firstObject];
-    DCHECK(firstLabel);
+    // If first suggestion is Google Pay logo animate it below the fold.
+    if (idx == 0U &&
+        suggestion.identifier == autofill::POPUP_ITEM_ID_GOOGLE_PAY_BRANDING) {
       const CGFloat firstLabelWidth =
-        CGRectGetWidth([firstLabel frame]) + kSuggestionHorizontalMargin;
+          [label systemLayoutSizeFittingSize:UILayoutFittingCompressedSize]
+              .width +
+          kSuggestionHorizontalMargin;
       dispatch_time_t popTime =
           dispatch_time(DISPATCH_TIME_NOW, 0.5 * NSEC_PER_SEC);
       __weak FormSuggestionView* weakSelf = self;
@@ -93,7 +114,8 @@ const CGFloat kSuggestionHorizontalMargin = 6;
                           animated:YES];
       });
     }
-  [super willMoveToSuperview:newSuperview];
+  };
+  [_suggestions enumerateObjectsUsingBlock:setupBlock];
 }
 
 - (NSArray*)suggestions {