Show toolbar buttons after omnibox resized

This CL changes the animations of the toolbar when the omnibox is
unfocused. The buttons are now appearing after the omnibox is resized.

Bug: 804748
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I149a004f4aa9e8d643ad2cc6d88de95855a66f83
Reviewed-on: https://chromium-review.googlesource.com/922102
Commit-Queue: Stepan Khapugin <stkhapugin@chromium.org>
Reviewed-by: Stepan Khapugin <stkhapugin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537260}

ios/chrome/browser/ui/orchestrator/omnibox_focus_orchestrator.mm

@@ -84,8 +84,11 @@
                    curve:UIViewAnimationCurveEaseInOut
               animations:showControls];
 
+    [slowAnimator addCompletion:^(UIViewAnimatingPosition finalPosition) {
+      [fastAnimator startAnimation];
+    }];
+
     [slowAnimator startAnimation];
-    [fastAnimator startAnimation];
   } else {
     contraction();
     showControls();