[iOS] Create a feature flag for incognito reauth.

Creates a new feature flag.

Bug: 1138886
Change-Id: I74d3308e668bffdcce43fed8aacffb778c4fbe2a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2475697
Commit-Queue: Stepan Khapugin <stkhapugin@chromium.org>
Auto-Submit: Stepan Khapugin <stkhapugin@chromium.org>
Reviewed-by: Robbie Gibson <rkgibson@google.com>
Cr-Commit-Position: refs/heads/master@{#819324}

chrome/browser/flag-metadata.json

@@ -1678,6 +1678,11 @@
     "owners": [ "bokan", "input-dev" ],
     "expiry_milestone": 80
   },
+  {
+    "name": "enable-incognito-authentication-ios",
+    "owners": [ "stkhapugin", "bling-flags" ],
+    "expiry_milestone": 90
+  },
   {
     "name": "enable-incognito-shortcut-on-desktop",
     "owners": [ "rhalavati", "chrome-privacy-core@google.com" ],

ios/chrome/browser/flags/about_flags.mm

@@ -651,6 +651,10 @@ const flags_ui::FeatureEntry kFeatureEntries[] = {
      flag_descriptions::kEditPasswordsInSettingsName,
      flag_descriptions::kEditPasswordsInSettingsDescription, flags_ui::kOsIos,
      FEATURE_VALUE_TYPE(password_manager::features::kEditPasswordsInSettings)},
+    {"enable-incognito-authentication-ios",
+     flag_descriptions::kIncognitoAuthenticationName,
+     flag_descriptions::kIncognitoAuthenticationDescription, flags_ui::kOsIos,
+     FEATURE_VALUE_TYPE(kIncognitoAuthentication)},
 };
 
 bool SkipConditionalFeatureEntry(const flags_ui::FeatureEntry& entry) {

ios/chrome/browser/flags/ios_chrome_flag_descriptions.cc

@@ -281,6 +281,12 @@ const char kFullscreenControllerBrowserScopedDescription[] =
     "When enabled, FullscreenController will be stored and retrieved using the "
     "Browser.";
 
+const char kIncognitoAuthenticationName[] =
+    "Device Authentication for Incognito";
+extern const char kIncognitoAuthenticationDescription[] =
+    "When enabled, a setting appears to enable biometric authentication for "
+    "accessing incognito.";
+
 const char kIllustratedEmptyStatesName[] = "Illustrated empty states";
 const char kIllustratedEmptyStatesDescription[] =
     "Display new illustrations and layout on empty states.";

ios/chrome/browser/flags/ios_chrome_flag_descriptions.h

@@ -240,6 +240,11 @@ extern const char kFullscreenSmoothScrollingDescription[];
 extern const char kFullscreenControllerBrowserScopedName[];
 extern const char kFullscreenControllerBrowserScopedDescription[];
 
+// Title and dscription for the flag to allow biometric authentication for
+// accessing incognito.
+extern const char kIncognitoAuthenticationName[];
+extern const char kIncognitoAuthenticationDescription[];
+
 // Title and description for the flag to enable new illustrations and
 // UI on empty states.
 extern const char kIllustratedEmptyStatesName[];

ios/chrome/browser/ui/ui_feature_flags.cc

@@ -73,3 +73,6 @@ const base::Feature kDefaultBrowserSettings{"DefaultBrowserSettings",
 // finished.
 const base::Feature kModernTabStrip{"ModernTabStrip",
                                     base::FEATURE_DISABLED_BY_DEFAULT};
+
+const base::Feature kIncognitoAuthentication{
+    "enable-incognito-authentication-ios", base::FEATURE_DISABLED_BY_DEFAULT};

ios/chrome/browser/ui/ui_feature_flags.h

@@ -81,4 +81,7 @@ extern const base::Feature kDefaultBrowserSettings;
 // finished. Flag to modernize the tabstrip without disturbing the existing one.
 extern const base::Feature kModernTabStrip;
 
+// Adds a setting to enable biometric authentication for incognito tabs.
+extern const base::Feature kIncognitoAuthentication;
+
 #endif  // IOS_CHROME_BROWSER_UI_UI_FEATURE_FLAGS_H_