[iOS] Add new feature flag and helper for popup presentation.

Adds new feature flag, kRefreshPopupPresentation, for UI refresh omnibox
popup presentation.

Bug: 821817
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: Ib4ed4f181e49849d5c5858b2457e14553f8d60af
Reviewed-on: https://chromium-review.googlesource.com/973308
Commit-Queue: Stepan Khapugin <stkhapugin@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#545039}

ios/chrome/browser/ui/ui_feature_flags.cc

@@ -4,6 +4,9 @@
 
 #include "ios/chrome/browser/ui/ui_feature_flags.h"
 
+const base::Feature kRefreshPopupPresentation{
+    "UIRefreshPopupPresentation", base::FEATURE_DISABLED_BY_DEFAULT};
+
 const base::Feature kUIRefreshPhase1{"UIRefreshPhase1",
                                      base::FEATURE_DISABLED_BY_DEFAULT};
 

ios/chrome/browser/ui/ui_feature_flags.h

@@ -7,6 +7,11 @@
 
 #include "base/feature_list.h"
 
+// Used to enable the UI Refresh omnibox popup presentation. This flag should
+// not be used directly. Instead use
+// ui_util::IsRefreshPopupPresentationEnabled().
+extern const base::Feature kRefreshPopupPresentation;
+
 // Used to enable the first phase of the UI refresh. This flag should not be
 // used directly. Instead use ui_util::IsUIRefreshPhase1Enabled().
 extern const base::Feature kUIRefreshPhase1;

ios/chrome/browser/ui/ui_util.h

@@ -39,6 +39,9 @@ CGFloat CurrentScreenWidth();
 // Returns true if the device is an iPhone X.
 bool IsIPhoneX();
 
+// Returns whether the UI Refresh Omnibox Popup presentation will be used.
+bool IsRefreshPopupPresentationEnabled();
+
 // Returns whether the first phase of the UI refresh will be displayed.
 bool IsUIRefreshPhase1Enabled();
 

ios/chrome/browser/ui/ui_util.mm

@@ -57,6 +57,10 @@ bool IsIPhoneX() {
           CGRectGetHeight([[UIScreen mainScreen] nativeBounds]) == 2436);
 }
 
+bool IsRefreshPopupPresentationEnabled() {
+  return base::FeatureList::IsEnabled(kRefreshPopupPresentation);
+}
+
 bool IsUIRefreshPhase1Enabled() {
   if (tests_hook::ForceUIRefreshPhase1())
     return true;