[ios] Add Default Browser Fullscreen Promo feature flag

This flag will be used as a killswitch for the default browser
fullscreen promo UI.

Bug: 1107489
Change-Id: I47159e1a1e1d4a8466b598d4d8236b41e942c6c6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2405892
Commit-Queue: Chris Lu <thegreenfrog@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#806359}

chrome/browser/flag-metadata.json

@@ -773,6 +773,11 @@
     "owners": [ "andrescj", "chromeos-gfx@google.com" ],
     "expiry_milestone": 88
   },
+  {
+    "name": "default-browser-fullscreen-promo",
+    "owners": [ "thegreenfrog", "bling-team@google.com" ],
+    "expiry_milestone": 89
+  },
   {
     "name": "delay-async-script-execution",
     "owners": [ "dom", "chrome-loading@google.com" ],

ios/chrome/browser/flags/about_flags.mm

@@ -691,6 +691,10 @@ const flags_ui::FeatureEntry kFeatureEntries[] = {
      flag_descriptions::kMobileIdentityConsistencyName,
      flag_descriptions::kMobileIdentityConsistencyDescription, flags_ui::kOsIos,
      FEATURE_VALUE_TYPE(signin::kMobileIdentityConsistency)},
+    {"default-browser-fullscreen-promo",
+     flag_descriptions::kDefaultBrowserFullscreenPromoName,
+     flag_descriptions::kDefaultBrowserFullscreenPromoDescription,
+     flags_ui::kOsIos, FEATURE_VALUE_TYPE(kDefaultBrowserFullscreenPromo)},
 };
 
 bool SkipConditionalFeatureEntry(const flags_ui::FeatureEntry& entry) {

ios/chrome/browser/flags/ios_chrome_flag_descriptions.cc

@@ -187,6 +187,13 @@ const char kDefaultToDesktopOnIPadDescription[] =
     "By default, on iPad, the desktop version of the web sites will be "
     "requested";
 
+const char kDefaultBrowserFullscreenPromoName[] =
+    "Fullscreen modal promo about the default browser feature";
+const char kDefaultBrowserFullscreenPromoDescription[] =
+    "When enabled, will allow for a fullscreen modal promo to be shown to "
+    "users informing them about the default browser feature and providing a "
+    "button that takes users to Settings.app to update their default browser.";
+
 const char kDetectMainThreadFreezeName[] = "Detect freeze in the main thread.";
 const char kDetectMainThreadFreezeDescription[] =
     "A crash report will be uploaded if the main thread is frozen more than "

ios/chrome/browser/flags/ios_chrome_flag_descriptions.h

@@ -151,6 +151,12 @@ extern const char kDcheckIsFatalDescription[];
 extern const char kDefaultToDesktopOnIPadName[];
 extern const char kDefaultToDesktopOnIPadDescription[];
 
+// Title and description for the flag to show a fullscreen modal promo with a
+// button that would send the users in the Settings.app to update the default
+// browser.
+extern const char kDefaultBrowserFullscreenPromoName[];
+extern const char kDefaultBrowserFullscreenPromoDescription[];
+
 // Title and description for the flag to control if a crash report is generated
 // on main thread freeze.
 extern const char kDetectMainThreadFreezeName[];

ios/chrome/browser/ui/main/default_browser_scene_agent.mm

@@ -4,9 +4,11 @@
 
 #import "ios/chrome/browser/ui/main/default_browser_scene_agent.h"
 
+#include "base/feature_list.h"
 #import "ios/chrome/app/application_delegate/app_state.h"
 #import "ios/chrome/browser/ui/commands/command_dispatcher.h"
 #import "ios/chrome/browser/ui/commands/whats_new_commands.h"
+#include "ios/chrome/browser/ui/ui_feature_flags.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
@@ -42,6 +44,11 @@
 
 - (void)sceneState:(SceneState*)sceneState
     transitionedToActivationLevel:(SceneActivationLevel)level {
+  if (!base::FeatureList::IsEnabled(kDefaultBrowserFullscreenPromo)) {
+    // Do nothing if the Default Browser Fullscreen Promo feature flag is not
+    // on.
+    return;
+  }
   AppState* appState = self.sceneState.appState;
   // Can only present UI when activation level is
   // SceneActivationLevelForegroundActive. Show the UI if user has met the

ios/chrome/browser/ui/ui_feature_flags.cc

@@ -62,3 +62,6 @@ const base::Feature kEnableFullPageScreenshot{
 
 const base::Feature kEnableAutofillPasswordReauthIOS{
     "EnableAutofillPasswordReauthIOS", base::FEATURE_DISABLED_BY_DEFAULT};
+
+const base::Feature kDefaultBrowserFullscreenPromo{
+    "DefaultBrowserFullscreenPromo", base::FEATURE_DISABLED_BY_DEFAULT};

ios/chrome/browser/ui/ui_feature_flags.h

@@ -68,4 +68,9 @@ extern const base::Feature kEnableFullPageScreenshot;
 // Feature flag that enables reauth for filling passwords;
 extern const base::Feature kEnableAutofillPasswordReauthIOS;
 
+// Feature flag that enables showing a fullscreen modal promo informing users
+// about the default browser feature that also provides a button to send the
+// users in the Settings.app to update the default browser.
+extern const base::Feature kDefaultBrowserFullscreenPromo;
+
 #endif  // IOS_CHROME_BROWSER_UI_UI_FEATURE_FLAGS_H_