Add feature flag for presenting SadTab UI in UIViewController.

Bug: 901563
Change-Id: Ia65425e4d47e79bfae1eb7bcd6f08aa0f4b641d5
Reviewed-on: https://chromium-review.googlesource.com/c/1321573Reviewed-by: Kurt Horimoto <kkhorimoto@chromium.org>
Commit-Queue: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606652}

ios/chrome/browser/BUILD.gn

@@ -135,6 +135,7 @@ source_set("browser") {
     "//ios/chrome/browser/ui/external_search:feature_flags",
     "//ios/chrome/browser/ui/fullscreen:feature_flags",
     "//ios/chrome/browser/ui/omnibox",
+    "//ios/chrome/browser/ui/sad_tab:features",
     "//ios/chrome/browser/ui/toolbar/public:feature_flags",
     "//ios/chrome/browser/ui/toolbar_container:feature_flags",
     "//ios/chrome/browser/web:feature_flags",

ios/chrome/browser/about_flags.mm

@@ -55,6 +55,7 @@
 #include "ios/chrome/browser/ssl/captive_portal_features.h"
 #include "ios/chrome/browser/ui/external_search/features.h"
 #import "ios/chrome/browser/ui/fullscreen/fullscreen_features.h"
+#include "ios/chrome/browser/ui/sad_tab/features.h"
 #import "ios/chrome/browser/ui/toolbar/public/features.h"
 #import "ios/chrome/browser/ui/toolbar_container/toolbar_container_features.h"
 #include "ios/chrome/browser/ui/ui_feature_flags.h"
@@ -384,6 +385,10 @@ const flags_ui::FeatureEntry kFeatureEntries[] = {
     {"toolbar-container", flag_descriptions::kToolbarContainerName,
      flag_descriptions::kToolbarContainerDescription, flags_ui::kOsIos,
      FEATURE_VALUE_TYPE(toolbar_container::kToolbarContainerEnabled)},
+    {"present-sad-tab-in-view-controller",
+     flag_descriptions::kPresentSadTabInViewControllerName,
+     flag_descriptions::kPresentSadTabInViewControllerDescription,
+     flags_ui::kOsIos, FEATURE_VALUE_TYPE(kPresentSadTabInViewController)},
     {"omnibox-popup-shortcuts",
      flag_descriptions::kOmniboxPopupShortcutIconsInZeroStateName,
      flag_descriptions::kOmniboxPopupShortcutIconsInZeroStateDescription,

ios/chrome/browser/ios_chrome_flag_descriptions.cc

@@ -286,6 +286,12 @@ const char kToolbarContainerDescription[] =
     "When enabled, the toolbars and their fullscreen animations will be "
     "managed by the toolbar container coordinator rather than BVC.";
 
+const char kPresentSadTabInViewControllerName[] =
+    "Present SadTab in UIViewController";
+const char kPresentSadTabInViewControllerDescription[] =
+    "When enabled, SadTab UI will be presented with UIViewController instead "
+    "of using WebState::ShowTransientView";
+
 const char kUnifiedConsentName[] = "Unified Consent";
 const char kUnifiedConsentDescription[] =
     "Enables a unified management of user consent for privacy-related "

ios/chrome/browser/ios_chrome_flag_descriptions.h

@@ -241,6 +241,11 @@ extern const char kSSOWithWKWebViewDescription[];
 extern const char kToolbarContainerName[];
 extern const char kToolbarContainerDescription[];
 
+// Title and description for the flag to use UIViewController for Sad Tab UI
+// presentation.
+extern const char kPresentSadTabInViewControllerName[];
+extern const char kPresentSadTabInViewControllerDescription[];
+
 // Title and description for the flag to enable the unified consent.
 extern const char kUnifiedConsentName[];
 extern const char kUnifiedConsentDescription[];

ios/chrome/browser/ui/sad_tab/BUILD.gn

@@ -11,6 +11,7 @@ source_set("sad_tab") {
     "sad_tab_view_controller.mm",
   ]
   deps = [
+    ":features",
     "//base",
     "//components/resources",
     "//components/strings",
@@ -30,6 +31,16 @@ source_set("sad_tab") {
   libs = [ "UIKit.framework" ]
 }
 
+source_set("features") {
+  sources = [
+    "features.cc",
+    "features.h",
+  ]
+  deps = [
+    "//base",
+  ]
+}
+
 source_set("coordinator") {
   configs += [ "//build/config/compiler:enable_arc" ]
   sources = [

ios/chrome/browser/ui/sad_tab/features.cc

+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ios/chrome/browser/ui/sad_tab/features.h"
+
+const base::Feature kPresentSadTabInViewController{
+    "PresentSadTabInViewController", base::FEATURE_DISABLED_BY_DEFAULT};

ios/chrome/browser/ui/sad_tab/features.h

+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef IOS_CHROME_BROWSER_UI_SAD_TAB_FEATURES_H_
+#define IOS_CHROME_BROWSER_UI_SAD_TAB_FEATURES_H_
+
+#include "base/feature_list.h"
+
+// Feature flag to enable SadTab UI presentation with UIViewController.
+extern const base::Feature kPresentSadTabInViewController;
+
+#endif  // IOS_CHROME_BROWSER_UI_SAD_TAB_FEATURES_H_