From Newsgroup: comp.mobile.android

Today I started this tutorial to help myself & others on Windows 10 &
on Android to block WebView using only the Windows PC & Android phone.
*How to replace Google's Android System WebView with that of Bromite?*
But I failed.

Miserably so.
So this is just a text log for others to learn from.

The hope is I missed something important that someone else can find.
If so, they can fix what I missed so we can block WebView for privacy.

Tested on Android13, Galaxy, unrooted, Android System WebView,
<com.google.android.webview>, Version 116.0.5845.163 (584516331)
<https://play.google.com/store/apps/details/?id=com.google.android.webview>

adb shell settings get global webview_provider

com.google.android.webview

Android13:Settings > Apps > Choose default apps > (Search) "webview"
That brings up two entries under "Your apps" of
Android System WebView (which is a link to its "App info")
Mobile data (Total = 74.44KB)(Foreground=0B)(Background=74.44KB)
Allow background data usage = on
Bromite Sytem WebView (which is a link to its "App info")
Mobile data (Total = 0B)(Foreground=0B)(Background=0B)
Allow background data usage = off

Android13:Settings > Developer options > WebView implementation.
Drat. There is only one option available which is
(o) Android System WebView

adb shell pm uninstall -k --user 0 com.google.android.webview

Success

adb reboot

Android13:Settings > Developer options > WebView implementation.
Drat. There is still only one option available which is
(o) Android System WebView

Apparently Samsung's firmware is locking WebView to the system default,
even after removing updates. Bromite System WebView is installed but
it's not recognized as a valid system implementation.

NetGuard > enabled
Hamburger > Settings > Advanced options
Manage system apps = on
Filter traffic = on
Scroll to "Android System WebView"
Tap the Wi-Fi icon to turn it red
Tap the mobile data icon to turn it red
You'd think that blocks WebView from accessing the internet.
It doesn't.
That's because it's not actually called via that package. Sigh.

Install "WebView Test"
<https://github.com/lsrom/webview-tester>
<https://github.com/lsrom/webview-tester/releases/tag/2.2>
Name: WebView-Tester.v2.2-release.apk
Size: 3110665 bytes (3037 KiB)
SHA256: 4C7C800B7B2AF1321BDCFA087EDE4F05967CA349D52EB2AA703249E8424BBB1B

On Android, run "WebView Test"
In the "CONFIG" tab is "http://"
Change that to http://cnn.com
Leave the other checkboxes unchecked for now.
Tap Load.
That switched to the "WEB VIEW" tab& loaded the CNN web page.
That confirmed Android System WebView is installed.
That confirmed the NetGuard block failed.
Drat. WebView is still functioning despite the block.

adb shell dumpsys webviewupdate

Current WebView Update Service state
Multiprocess enabled: true
Current WebView package (name, version): (com.google.android.webview, 116.0.5845.163)
Minimum targetSdkVersion: 33
Minimum WebView version code: 556311633
Number of relros started: 2
Number of relros finished: 2
WebView package dirty: false
Any WebView package installed: true
Preferred WebView package (name, version): (com.google.android.webview, 116.0.5845.163)
WebView packages:
Valid package com.google.android.webview (versionName: 116.0.5845.163, versionCode: 584516331, targetSdkVersion: 34) is installed/enabled for all users
com.google.android.webview.beta is NOT installed.
com.google.android.webview.dev is NOT installed.
com.google.android.webview.canary is NOT installed.
com.google.android.webview.debug is NOT installed.
com.android.webview is NOT installed.

The "WebView Test" log file shows I failed to block it.
<content://cz.lsrom.webviewtest.provider/webview_logs/Android/data/cz.lsrom.webviewtest/files/2025-09-05-logs.txt>

adb pull /sdcard/Android/data/cz.lsrom.webviewtest/files/2025-09-05-logs.txt

This log file confirms that the WebView is actively executing JavaScript,
loading dynamic content, and encountering runtime errors. That means WebView
is functioning, and NetGuard is not blocking it at the network level
(at least not completely). Sigh.

When an app uses WebView, the network requests are made by the hosting
app's process, not by the WebView package itself. The WebView code is
just a rendering engine loaded into that app. So the traffic will appear
to come from the app using it (for example, your email client, a news app,
or a social media app), not from com.google.android.webview.

The only time blocking the WebView package's network access would have
an effect is if WebView itself tried to download updates or fetch remote resources outside of an app context, which is rare. I failed. Sorry.

If you know how to switch Android WebView to Bromite Webview using
the Windows PC and Android, please let me know what I don't know.
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