chore(runway): cherry-pick feat: legacy-ios-feature-flag cp-7.71.0 (#27848)

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## **Description**
Support webcredential for ios google login
Part 2/4 - Add feature flag 

This pr add feature flag for the ios google login


PR list
Part 1/ 4 - #27741
Part 2/ 4 - #27848
Part 3/ 4 - #27850
Part 4/ 4 - TBA

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CHANGELOG entry: added legacyIosGoogleConfigEnabled feature flag

## **Related issues**

Fixes:

## **Manual testing steps**

```gherkin
Feature: my feature name

  Scenario: user [verb for user action]
    Given [describe expected initial app state]

    When user [verb for user action]
    Then [describe expected outcome]
```

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<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Low Risk**
> Low risk: adds a new remote feature flag and selector with env
override, without changing authentication flow yet; main risk is
misconfiguration since the selector defaults to enabled.
> 
> **Overview**
> Adds a new remote feature flag, `legacyIosGoogleConfigEnabled`,
including registry metadata and a dedicated selector
`selectLegacyIosGoogleConfigEnabled` (defaulting to `true`) that can be
force-overridden via `MM_LEGACY_IOS_GOOGLE_CONFIG_ENABLED`.
> 
> Includes unit tests covering default/remote/env override behavior, and
updates `babel.config.tests.js` to avoid inlining env vars for the new
selector and its tests.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
ca7e813. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: ieow

app/constants/featureFlags.ts

@@ -15,6 +15,7 @@ export enum FeatureFlagNames {
   tokenDetailsV2Buttons = 'tokenDetailsV2Buttons',
   tokenDetailsV2ButtonLayout = 'tokenDetailsV2ButtonLayout',
   complianceEnabled = 'complianceEnabled',
+  legacyIosGoogleConfigEnabled = 'legacyIosGoogleConfigEnabled',
 }
 
 export const DEFAULT_FEATURE_FLAG_VALUES: Partial<

app/selectors/featureFlagController/legacyIosGoogleConfig/index.test.ts

@@ -0,0 +1,56 @@
+import {
+  DEFAULT_LEGACY_IOS_GOOGLE_CONFIG_ENABLED,
+  selectLegacyIosGoogleConfigEnabled,
+} from '.';
+import { FeatureFlagNames } from '../../../constants/featureFlags';
+
+describe('Legacy iOS Google Config Feature Flag Selector', () => {
+  const originalEnv = process.env.MM_LEGACY_IOS_GOOGLE_CONFIG_ENABLED;
+
+  beforeEach(() => {
+    delete process.env.MM_LEGACY_IOS_GOOGLE_CONFIG_ENABLED;
+  });
+
+  afterAll(() => {
+    if (originalEnv === undefined) {
+      delete process.env.MM_LEGACY_IOS_GOOGLE_CONFIG_ENABLED;
+      return;
+    }
+
+    process.env.MM_LEGACY_IOS_GOOGLE_CONFIG_ENABLED = originalEnv;
+  });
+
+  it('returns the default value when the remote flag is missing', () => {
+    const result = selectLegacyIosGoogleConfigEnabled.resultFunc({});
+
+    expect(result).toBe(DEFAULT_LEGACY_IOS_GOOGLE_CONFIG_ENABLED);
+  });
+
+  it('returns the remote flag value when present', () => {
+    const result = selectLegacyIosGoogleConfigEnabled.resultFunc({
+      [FeatureFlagNames.legacyIosGoogleConfigEnabled]: false,
+    });
+
+    expect(result).toBe(false);
+  });
+
+  it('allows the local env var to force enable the legacy config', () => {
+    process.env.MM_LEGACY_IOS_GOOGLE_CONFIG_ENABLED = 'true';
+
+    const result = selectLegacyIosGoogleConfigEnabled.resultFunc({
+      [FeatureFlagNames.legacyIosGoogleConfigEnabled]: false,
+    });
+
+    expect(result).toBe(true);
+  });
+
+  it('allows the local env var to force disable the legacy config', () => {
+    process.env.MM_LEGACY_IOS_GOOGLE_CONFIG_ENABLED = 'false';
+
+    const result = selectLegacyIosGoogleConfigEnabled.resultFunc({
+      [FeatureFlagNames.legacyIosGoogleConfigEnabled]: true,
+    });
+
+    expect(result).toBe(false);
+  });
+});

app/selectors/featureFlagController/legacyIosGoogleConfig/index.ts

@@ -0,0 +1,26 @@
+import { hasProperty } from '@metamask/utils';
+import { createSelector } from 'reselect';
+import { FeatureFlagNames } from '../../../constants/featureFlags';
+import { getFeatureFlagValue } from '../env';
+import { selectRemoteFeatureFlags } from '..';
+
+export const DEFAULT_LEGACY_IOS_GOOGLE_CONFIG_ENABLED = true;
+
+export const selectLegacyIosGoogleConfigEnabled = createSelector(
+  selectRemoteFeatureFlags,
+  (remoteFeatureFlags) => {
+    const remoteValue = hasProperty(
+      remoteFeatureFlags,
+      FeatureFlagNames.legacyIosGoogleConfigEnabled,
+    )
+      ? Boolean(
+          remoteFeatureFlags[FeatureFlagNames.legacyIosGoogleConfigEnabled],
+        )
+      : DEFAULT_LEGACY_IOS_GOOGLE_CONFIG_ENABLED;
+    return getFeatureFlagValue(
+      // Use direct env access so Babel can inline this value in app builds.
+      process.env.MM_LEGACY_IOS_GOOGLE_CONFIG_ENABLED,
+      remoteValue,
+    );
+  },
+);

babel.config.tests.js

@@ -37,6 +37,8 @@ const newOverrides = [
       'app/components/UI/Ramp/hooks/useRampTokens.test.ts',
       'app/components/Views/confirmations/hooks/pay/useTransactionPayWithdraw.ts',
       'app/components/Views/confirmations/hooks/pay/useTransactionPayWithdraw.test.ts',
+      'app/selectors/featureFlagController/legacyIosGoogleConfig/index.ts',
+      'app/selectors/featureFlagController/legacyIosGoogleConfig/index.test.ts',
       'app/util/environment.ts',
       'app/util/environment.test.ts',
       'app/core/Engine/controllers/rewards-controller/utils/rewards-api-url.ts',

tests/feature-flags/feature-flag-registry.ts

@@ -2829,6 +2829,14 @@ export const FEATURE_FLAG_REGISTRY: Record<string, FeatureFlagRegistryEntry> = {
     status: FeatureFlagStatus.Active,
   },
 
+  legacyIosGoogleConfigEnabled: {
+    name: 'legacyIosGoogleConfigEnabled',
+    type: FeatureFlagType.Remote,
+    inProd: true,
+    productionDefault: true,
+    status: FeatureFlagStatus.Active,
+  },
+
   metalCardCheckoutEnabled: {
     name: 'metalCardCheckoutEnabled',
     type: FeatureFlagType.Remote,