[iOS] Remove close-last-tab tab grid experiment.

The closing-last-incognito-tab experiment has been default-on for nearly a year.

This CL deletes the flag.

Bug: 893314
Change-Id: Iafb145e66c8279cca034c04238b7dc3dca1f92f7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1807247Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#697591}

ios/chrome/browser/flags/about_flags.mm

@@ -377,10 +377,6 @@ const flags_ui::FeatureEntry kFeatureEntries[] = {
     {"use-multilogin-endpoint", flag_descriptions::kUseMultiloginEndpointName,
      flag_descriptions::kUseMultiloginEndpointDescription, flags_ui::kOsIos,
      FEATURE_VALUE_TYPE(kUseMultiloginEndpoint)},
-    {"closing-last-incognito-tab",
-     flag_descriptions::kClosingLastIncognitoTabName,
-     flag_descriptions::kClosingLastIncognitoTabDescription, flags_ui::kOsIos,
-     FEATURE_VALUE_TYPE(kClosingLastIncognitoTab)},
     {"omnibox-on-device-head-suggestions",
      flag_descriptions::kOmniboxOnDeviceHeadSuggestionsName,
      flag_descriptions::kOmniboxOnDeviceHeadSuggestionsDescription,

ios/chrome/browser/flags/ios_chrome_flag_descriptions.cc

@@ -120,12 +120,6 @@ const char kBrowserContainerKeepsContentViewDescription[] =
     "When enable, the browser container keeps the content view in the view "
     "hierarchy, to avoid WKWebView from being unloaded from the process.";
 
-// TODO(crbug.com/893314) : Remove this flag.
-const char kClosingLastIncognitoTabName[] = "Closing Last Incognito Tab";
-const char kClosingLastIncognitoTabDescription[] =
-    "Automatically switches to the regular tabs panel in the tab grid after "
-    "closing the last incognito tab";
-
 const char kCollectionsCardPresentationStyleName[] =
     "Card style presentation for Collections.";
 const char kCollectionsCardPresentationStyleDescription[] =

ios/chrome/browser/flags/ios_chrome_flag_descriptions.h

@@ -92,11 +92,6 @@ extern const char kBreakpadNoDelayInitialUploadDescription[];
 extern const char kBrowserContainerKeepsContentViewName[];
 extern const char kBrowserContainerKeepsContentViewDescription[];
 
-// Title and description for the flag to enable automatically switching to the
-// regular tabs after closing the last incognito tab.
-extern const char kClosingLastIncognitoTabName[];
-extern const char kClosingLastIncognitoTabDescription[];
-
 // Title and description for the flag that controls whether Collections are
 // presented using the new iOS13 Card style or the custom legacy one.
 extern const char kCollectionsCardPresentationStyleName[];

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

@@ -27,7 +27,6 @@
 #import "ios/chrome/browser/ui/tab_grid/transitions/grid_transition_layout.h"
 #import "ios/chrome/browser/ui/table_view/chrome_table_view_styler.h"
 #import "ios/chrome/browser/ui/util/rtl_geometry.h"
-#include "ios/chrome/browser/ui/util/ui_util.h"
 #import "ios/chrome/browser/ui/util/uikit_ui_util.h"
 #import "ios/chrome/common/colors/semantic_color_names.h"
 #import "ios/chrome/common/ui_util/constraints_ui_util.h"
@@ -1118,8 +1117,7 @@ NSUInteger GetPageIndexFromPage(TabGridPage page) {
     // No assumption is made as to the state of the UI. This method can be
     // called with an incognito view controller and a current page that is not
     // the incognito tabs.
-    if (IsClosingLastIncognitoTabEnabled() && count == 0 &&
-        self.currentPage == TabGridPageIncognitoTabs) {
+    if (count == 0 && self.currentPage == TabGridPageIncognitoTabs) {
       // Show the regular tabs to the user if the last incognito tab is closed.
       if (self.viewLoaded && self.view.window) {
         // Visibly scroll to the regular tabs panel after a slight delay when

ios/chrome/browser/ui/ui_feature_flags.cc

@@ -4,10 +4,6 @@
 
 #include "ios/chrome/browser/ui/ui_feature_flags.h"
 
-// TODO(crbug.com/893314) : Remove this flag.
-const base::Feature kClosingLastIncognitoTab{"ClosingLastIncognitoTab",
-                                             base::FEATURE_ENABLED_BY_DEFAULT};
-
 const base::Feature kBrowserContainerKeepsContentView{
     "BrowserContainerKeepsContentView", base::FEATURE_DISABLED_BY_DEFAULT};
 

ios/chrome/browser/ui/ui_feature_flags.h

@@ -7,10 +7,6 @@
 
 #include "base/feature_list.h"
 
-// Feature to automatically switch to the regular tabs panel in tab grid after
-// closing the last incognito tab.
-extern const base::Feature kClosingLastIncognitoTab;
-
 // Feature to retain the contentView in the browser container.
 extern const base::Feature kBrowserContainerKeepsContentView;
 

ios/chrome/browser/ui/util/ui_util.h

@@ -39,10 +39,6 @@ CGFloat CurrentScreenWidth();
 // Returns true if the device is an iPhone X.
 bool IsIPhoneX();
 
-// Returns whether the flag is enabled for switching to the regular tabs panel
-// in tab switcher when the last incognito tab is closed.
-bool IsClosingLastIncognitoTabEnabled();
-
 // Returns the approximate corner radius of the current device.
 CGFloat DeviceCornerRadius();
 

ios/chrome/browser/ui/util/ui_util.mm

@@ -59,11 +59,6 @@ bool IsIPhoneX() {
           (height == 2436 || height == 2688 || height == 1792));
 }
 
-// TODO(crbug.com/893314) : Remove this flag.
-bool IsClosingLastIncognitoTabEnabled() {
-  return base::FeatureList::IsEnabled(kClosingLastIncognitoTab);
-}
-
 CGFloat DeviceCornerRadius() {
   return IsIPhoneX() ? 40.0 : 0.0;
 }