[ios] TopAlignedImageView bug fix

The layout needs updating whenever a new
image is set.

Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: If7e9d731f31bec7d28198a6f06275abd36071185
Reviewed-on: https://chromium-review.googlesource.com/954502Reviewed-by: edchin <edchin@chromium.org>
Reviewed-by: Sergio Collazos <sczs@chromium.org>
Commit-Queue: Sergio Collazos <sczs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542555}

ios/chrome/browser/ui/tab_grid/top_aligned_image_view.mm

@@ -53,6 +53,7 @@
 
 - (void)setImage:(UIImage*)image {
   self.innerImageView.image = image;
+  [self setNeedsLayout];
 }
 
 - (UIImage*)image {