Show blank page instead of NTP/site preview when switching apps

[Brave-Matt]

Description:

When switching apps on iOS, Brave should show a blank screen (or innocuous icon/image, etc) when browser is in Private mode and switching between apps, rather than showing the NTP, address bar, icons or any other information currently contained on the browser.

Internal conversation:
https://bravesoftware.slack.com/archives/C06UXF3KJ/p1670356534286049
Community request for the feature:
https://community.brave.com/t/exiting-switching-tab-will-not-hide/448076/6

[hffvld]

Verified on iPhone 14 using version(s):

Device/OS: iPhone 14 [iOS 17.0]
Brave build: 1.58 (23.9.19.14)
BraveCore: 1.58.124 (117.0.5938.62)

Filed follow-up issue #8095

Standard Tab

STEPS:

1. Launch Brave
2. Open NTP in Standard Tab mode
3. Use the app switch gesture to see all opened apps > Verify
4. Return to Brave > Open any website
5. Use the app switch gesture to see all opened apps > Verify

ACTUAL RESULTS:

• Verified that all info is shown for NTP in Standard Tab mode when switching apps
• Verified that all info is shown for websites in Standard Tab mode when switching apps
• Verified the same behavior when Brave is in foreground and background

---

NTP	YT	Wikipedia

Private Tab

STEPS:

1. Launch Brave
2. Open NTP in Private Tab mode
3. Use the app switch gesture to see all opened apps > Verify
4. Return to Brave > Open any website
5. Use the app switch gesture to see all opened apps > Verify
6. Tap tab switch button > Use the app switch gesture to see all opened apps > Verify
7. Open NTP > Tap Search button > Use the app switch gesture to see all opened apps > Verify

ACTUAL RESULTS:

• Verified that a blank screen is shown for NTP in Private Tab mode when switching apps
• Verified that a blank screen is shown for websites in Private Tab mode when switching apps
• Verified the same behavior when Brave is in foreground and background

---

NTP	Wikipedia	YT	Tabs switch