Enable the title/URL swap flag on Mac.

Swapping title and URL is already done for the experimental vertical
layout. This new flag (chrome://flags/#omnibox-ui-swap-title-and-url)
is intended to enable the same behavior in the default horizontal
layout.

Bug: 
Change-Id: I6c2eca5ca11fef7518a88704b56de03e38f4f001
Reviewed-on: https://chromium-review.googlesource.com/695822Reviewed-by: Rachel Blum <groby@chromium.org>
Commit-Queue: Justin Donnelly <jdonnelly@chromium.org>
Cr-Commit-Position: refs/heads/master@{#505903}

chrome/browser/ui/cocoa/omnibox/omnibox_popup_cell.mm

@@ -421,8 +421,10 @@ NSAttributedString* CreateClassifiedAttributedString(
       if (!match.description.empty()) {
         // Swap the contents and description of non-search suggestions in
         // vertical layouts.
-        BOOL swapMatchText = base::FeatureList::IsEnabled(
-                                 omnibox::kUIExperimentVerticalLayout) &&
+        BOOL swapMatchText = (base::FeatureList::IsEnabled(
+                                  omnibox::kUIExperimentVerticalLayout) ||
+                              base::FeatureList::IsEnabled(
+                                  omnibox::kUIExperimentSwapTitleAndUrl)) &&
                              !AutocompleteMatch::IsSearchType(match.type);
 
         description_ = [CreateClassifiedAttributedString(