feat: verify webview version and prevent loading blank screen

[Fandroid745]

Purpose / Description

This is enhancement to prevent the Blank Screen bug on devices with an outdated WebView (e.g-old huawei models) by checking the WebView version. It will show the alert dialog when the user with an outdated webview tries to import decks.

Fixes

This pr fixes the issue #19914

Approach

1. implemented logic to extract the Chromium version from the User-Agent string. This correctly identifies outdated engines even when OEMs report inflated versionCode values (e.g., manifest code 21311 ( downloaded and verified the manifest.xml in android studio https://www.apkmirror.com/apk/huawei/huawei-webview-2/huawei-webview-15-0-4-326-release/)

2. Added a requiresModernWebView() hook in PageFragment (defaulting to false) and removed checkWebViewVersion(this) from DeckPicker as it was causing dialog to show on app launch in main screen

3. Changed checkWebviewVersion function in WebViewUtils.kt to return a Boolean. It returns true only if the webview is outdated and a warning dialog is displayed.

4. In PageFragment.onViewCreated, if the guard triggers, the app immediately calls onBackPressed() and returns. This physically prevents the WebView from initializing, avoiding the "White Screen" crash on incompatible devices.

How Has This Been Tested?

Unit Testing:
Included test cases using real-world version codes from Honor/Huawei bug reports (Manifest code 21311 and threshold 450M) to ensure the User-Agent audit correctly identifies outdated webviews
All the tests pass:

./gradlew :AnkiDroid:testPlayDebugUnitTest --tests "com.ichi2.utils.WebViewUtilsTest"
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[Incubating] Problems report is available at: file:///home/dhanush/Anki-Android/build/reports/problems/problems-report.html
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BUILD SUCCESSFUL in 12s
135 actionable tasks: 8 executed, 127 up-to-date

Learning (optional, can help others)

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Checklist

Please, go through these checks before submitting the PR.

• You have a descriptive commit message with a short title (first line, max 50 chars).
• You have commented your code, particularly in hard-to-understand areas
• You have performed a self-review of your own code
• UI changes: include screenshots of all affected screens (in particular showing any new or changed strings)
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[david-allison]

This doesn't look correct.

I'll need strong evidence of testing, (ideally with a unit test), using values from a real Huawei device before I approve this.

[david-allison]

This breaks the app more than it was previously. Some pages would work on lower APIs

[Fandroid745]

I have added the unit tests and the warning dialog will only be displayed if the user tries importing with an outdated webview version and not on the main screen

[david-allison]

Cheers, what's the source of the test data?

[Fandroid745]

Cheers, what's the source of the test data?

2113 was the version code I got after analyzing the webview apk 15.0.4 from the apk mirror. 450 M is just a threshold that I am using, I don't know for sure if it is equal to 78 or not it is a guess.

[david-allison]

Cheers. Could you provide a link in the source code

[AnEht]

apk link for testing
https://drive.google.com/file/d/1saeZe9_IgU8zuCQXY5sI7wNAWu0-_4G_/view?usp=drive_link

This is the screen shoot of what it runs on the honor device.
https://pan.huang1111.cn/s/MN1Aoix

[david-allison]

@Fandroid745 What was the intention of the debug APK?

Given AnEht has updated the WebView, diagnostic information is likely to be out of date

[AnEht]

Given AnEht has updated the WebView, diagnostic information is likely to be out of date

I used an Honor device that had not been updated and a Huawei device that was updated before.

This is the screen shoot of what it runs on the honor device.

This was performed on my unupdated Honor device, which showed no changes and no warning dialogs.

[david-allison]

@AnEht oh, fantastic, thanks so much

On the 'bad' device, can you go to: AnkiDroid: sidebar - help - get help - send troubleshooting report

Then settings - about - copy debug info and paste it here

[Fandroid745]

@Fandroid745 What was the intention of the debug APK?

Given AnEht has updated the WebView, diagnostic information is likely to be out of date

I thought the debug apk will help verify if it works on unupdated honor phones or not

[AnEht]

AnkiDroid Version = 2.23.1 (3f3133b)
Backend Version = 0.1.62-anki25.09.2 (25.09.2 3890e12c9e48c028c3f12aa58cb64bd9f8895e30)
Android Version = 10 (SDK 29)
ProductFlavor = play
Device Info = HUAWEI | HUAWEI | HWTAS | TAS-AL00 | TAS-AL00 | kirin990
Webview User Agent = Mozilla/5.0 (Linux; Android 10; TAS-AL00 Build/HUAWEITAS-AL00; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/114.0.5735.196 Mobile Safari/537.36
ACRA UUID = aed8344c-9c29-4b4b-8b94-de0c7b1a9f2b
FSRS = 5.1.0 (Enabled: true)
Crash Reports Enabled = true