[ios] Update fake omnibox width on view appear.

Bug: 789658
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: Ie58dc41f31ade019ca2ea93cd9f28a89ee6e50b6
Reviewed-on: https://chromium-review.googlesource.com/804154Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Justin Cohen <justincohen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521349}

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

@@ -257,9 +257,11 @@ BOOL ShouldCellsBeFullWidth(UITraitCollection* collection) {
 
 - (void)viewWillAppear:(BOOL)animated {
   [super viewWillAppear:animated];
-  // Reload data to ensure the Most Visited tiles are correctly positionned, in
-  // particular during a rotation while a ViewController is presented in front
-  // of the NTP.
+  // Reload data to ensure the Most Visited tiles and fakeOmnibox are correctly
+  // positionned, in particular during a rotation while a ViewController is
+  // presented in front of the NTP.
+  [self.headerSynchronizer
+      updateFakeOmniboxOnNewWidth:self.collectionView.bounds.size.width];
   [self.collectionView.collectionViewLayout invalidateLayout];
 }