change(android): use webview asset loader 🍒 🏠

[jahorton]

Cherry-pick-of: #16146
Cherry-pick-of: #16188
Cherry-pick-of: #16184
Relates-to: #13862
Follows: #16604
Fixes: KEYMAN-WEB-RB
Fixes: KEYMAN-WEB-Z8
Fixes: KEYMAN-WEB-MD
Fixes: KEYMAN-WEB-YV
Fixes: KEYMAN-WEB-YW
Fixes: KEYMAN-WEB-YX

Use WebViewAssetLoader in order to stop using file:// URLs for loading all assets in the keyboard WebView. In this case, for lexical models, as an attempt to resolve (sample) error: Error occurred when attempting to load dictionary NetworkError: Failed to execute 'importScripts' on 'WorkerGlobalScope': The script at 'file:///data/user/0/com.tavultesoft.kmapro/app_data/models/nrc.en.mtnt/nrc.en.mtnt.model.js' failed to load.

While we originally made the change to using WebViewAssetLoader in order to support use of the window.fetch() API for keyboard loading in version 19, we hope that the same solution will address the crash report when loading of predictive-text models on Android in Chrome 152.0 and later versions. This error was sporadically happening with earlier versions of Chrome (20 per month or so) but is frequent now -- we've been getting nearly 10,000 error reports daily.

Per MDN reference, NetworkError is received when an incorrect MIME type is used. While this error does not seem to be happening on our test devices or any device we have access to, we theorize that there could be some environmental cause for file:/// based URLs (for lexical models) being labelled with incorrect MIME-type info (another app with bogus registered MIME type for .js? something like that?).

Using an asset-loader scheme would provide an https://-like URL and a "server" that would provide proper MIME-info, resolving what we now hope to be the underlying cause of the frequent error report. It's hard to know for sure at present due to our current inability to reproduce the issue.

Build-bot: skip release:android

User Testing

TEST_SMOKE: Verify that the Android app loads properly and that it properly swaps among installed keyboards and lexical models without issue. If a keyboard that should have an associated model does not display predictive text, FAIL this test. Verify that the correct font is used in the OSK and the input area in the Keyman app (e.g. try with the 'Lakeside' keyboard).

TEST_FIRSTVOICES: install FirstVoices Keyboards for Android apk. Try different keyboards, verify that the OSK and displayed text look correct. For SENCOTEN, verify that predictive text is working.

[keymanapp-test-bot]

User Test Results

Test specification and instructions

• ✅ TEST_SMOKE (PASSED) (notes)
• ✅ TEST_FIRSTVOICES (PASSED) (notes)

Test Artifacts

• Android
  • Keyman for Android apk
  • FirstVoices Keyboards for Android apk
  • KeyboardHarness apk
  • KMSample1 apk
  • KMSample2 apk

[mcdurdin]

Test Results

• TEST_SMOKE (PASS): Installed app, tested in-app and system keyboard, sil_euro_latin, khmer_angkor, and luo_lakeside. Predictive text worked no problems with sil_euro_latin and khmer_angkor. Fonts loaded correctly for all three keyboards - in OSK and text area in Keyman app. Connected to DevTools, verified no errors, appassets.androidplatform.net domain. Everything looks good.
• TEST_FIRSTVOICES (PASS): Installed app, tested system keyboard, sil_euro_latin, fv_sencoten. Predictive text worked correctly for both keyboards. All looks correct. Connected to DevTools, verified no errors, appassets.androidplatform.net domain. No errors encountered.

[Meng-Heng]

Test Specs

1. Keyman device: OPPO A60 Android v16
2. FirstVoices device: Android Studio: Pixel 6a API 33

Test Results

• TEST_SMOKE (PASSED):

1. Keyman launch with EuroLatin (SIL) keyboard with predictive text -> Dismiss Get Started instructions
2. Go to Settings -> Click 'Install Keyboard or Dictionary' -> Search Khmer -> Install Khmer Angkor
3. VERIFIED: Khmer Angkor keyboard loads with predictive text
4. Switching keyboards work as expected
5. Go to Settings -> Install Keyboard or Dictionary -> Search Lakeside -> Install Lakeside
6. Lakeside keyboard loads with Keyman banner
7. Type qwe (positional keys on the keyboard) with the Lakeside keyboard
8. Switch to Khmer Angkor and EuroLatin (SIL) keyboard
9. VERIFIED:
   • The correct font applied to OSK and Input area for Lakeside keyboard
   • Switching keyboards with the predictive text rendered accordingly.

• TEST_FIRSTVOICES (PASSED):

1. FirstVoices launch -> Select keyboards -> Atlantic: Mi'gmawi'simg + BC Coast: SENCOTEN
2. Follow all of the 3 setup requirements in FirstVoices app
3. Open Chrome -> Start Typing
4. VERIFIED: Predictive text work as expected; predict words according to the typed text. OSK and displayed text look correct.

[keyman-server]

Changes in this pull request will be available for download in Keyman version 18.0.252

[mcdurdin]

One event received in 18.0.252 last night, which appears unrelated but was bundled under the same issue in Sentry:

Error:  Error occurred when attempting to load dictionary
SyntaxError: Invalid or unexpected token

{
  configReport: {
    embeddingApp: AndroidMobile,
      hostDevice: {
        browser: native,
        formFactor: phone,
        OS: android,
        touchable: true
      },
    initialized: true,
    keymanEngine: app/webview
  },

  keyboard: {
    id: sil_euro_latin::sil_euro_latin,
    langId: en,
    version: 2.0.4
  },

  model: {
    id: nrc.en.mtnt
  },

  osk: {
    banner: suggestion,
    layer: shift
  }
}

Unclear if the error is arising from nrc.en.mtnt or from another model they have installed on their device (the error message could list the model name!)