TF-4099 Mobile adding an attachment causes composer UI issues

[dab246]

Issue

#4099

Root cause

• Log analysis:

[ERROR:android_webview/browser/aw_browser_terminator.cc:165]
Renderer process (14064) crash detected (code -1).
[ERROR:android_webview/browser/aw_browser_terminator.cc:113]
Render process (14064) kill (OOM or update) wasn't handled by all associated webviews, killing application.

This is a typical crash of Android WebView renderer being OOM (Out Of Memory) or being force-killed due to low-memory policy.

Special:

Process com.linagora.android.teammail (pid 12911) has died: svc +1 LAST
skip restart com.linagora.android.teammail because this device is a lowmemory device!

Confirmed MIUI (system_server) killed the process to reclaim memory, as the device recognized it as a “lowmemory device”.

• Conclude:

flutter_inappwebview creates its own sandbox renderer (Chromium engine) -> consumes a lot of RAM.

When file_picker turns on Intent.ACTION_OPEN_DOCUMENT, Android temporarily switches foreground to another app → causing MIUI or Android low-memory killer to think your app is in the background → kill WebView renderer.

Then WebView cannot recover because Chromium sandbox is dead → Flutter is terminated.

Workaround

• Reduce WebView memory footprint
• Enable android:largeHeap="true" in AndroidManifest => Allow process to keep more RAM, limit OOM kill when DocumentsUI is open.

[github-actions]

This PR has been deployed to https://linagora.github.io/tmail-flutter/4100.