[ios] Update NTP header view constraints on view load.

Bug: 859555
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I6c4c564f12ee0acb89fdcc9538f89e4277f1461a
Reviewed-on: https://chromium-review.googlesource.com/1139528Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Justin Cohen <justincohen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575605}

ios/chrome/browser/ui/content_suggestions/content_suggestions_header_controlling.h

@@ -35,6 +35,9 @@
 // Calls layoutIfNeeded on the header.
 - (void)layoutHeader;
 
+// Update any dynamic constraints.
+- (void)updateConstraints;
+
 // Returns the Y value to use for the scroll view's contentOffset when scrolling
 // the omnibox to the top of the screen.
 - (CGFloat)pinnedOffsetY;

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

@@ -207,6 +207,10 @@ initWithCollectionController:
   }
 }
 
+- (void)updateConstraints {
+  [self.headerController updateConstraints];
+}
+
 - (void)unfocusOmnibox {
   [self.headerController unfocusOmnibox];
 }

ios/chrome/browser/ui/content_suggestions/content_suggestions_header_synchronizing.h

@@ -21,6 +21,9 @@
 // Unfocuses the omnibox.
 - (void)unfocusOmnibox;
 
+// Update any dynamic constraints.
+- (void)updateConstraints;
+
 // Returns the Y value to use for the scroll view's contentOffset when scrolling
 // the omnibox to the top of the screen.
 - (CGFloat)pinnedOffsetY;

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

@@ -135,10 +135,7 @@ const UIEdgeInsets kSearchBoxStretchInsets = {3, 3, 3, 3};
         if (IsSplitToolbarMode()) {
           [self.toolbarDelegate setScrollProgressForTabletOmnibox:1];
         }
-
-        // Update the doodle top margin to the new -doodleTopMargin value.
-        self.doodleTopMarginConstraint.constant =
-            content_suggestions::doodleTopMargin(YES);
+        [self updateConstraints];
       };
 
   [coordinator animateAlongsideTransition:transition completion:nil];
@@ -198,6 +195,12 @@ const UIEdgeInsets kSearchBoxStretchInsets = {3, 3, 3, 3};
   [self.headerView layoutIfNeeded];
 }
 
+// Update the doodle top margin to the new -doodleTopMargin value.
+- (void)updateConstraints {
+  self.doodleTopMarginConstraint.constant =
+      content_suggestions::doodleTopMargin(YES);
+}
+
 - (CGFloat)pinnedOffsetY {
   CGFloat headerHeight = content_suggestions::heightForLogoHeader(
       self.logoIsShowing, self.promoCanShow, YES);

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

@@ -193,6 +193,7 @@ BOOL ShouldCellsBeFullWidth(UITraitCollection* collection) {
       updateMostVisitedForSize:self.collectionView.bounds.size];
   [self.headerSynchronizer
       updateFakeOmniboxOnNewWidth:self.collectionView.bounds.size.width];
+  [self.headerSynchronizer updateConstraints];
   [self.collectionView reloadData];
   if (ShouldCellsBeFullWidth(
           [UIApplication sharedApplication].keyWindow.traitCollection)) {