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Title: chromium: window from a second launch does not repaint after
maximize when DESKTOP_STARTUP_ID is set (X11, KDE)

Package: chromium

Version: Version: 153.0.8010.52-1~deb13u1

Severity: normal

---

System

- Chromium 153.0.8010.52, Debian 13 (trixie), x86_64
- Kernel: Linux 6.12.107+deb13-amd64
- Desktop: KDE Plasma, KWin, X11 session
- Ozone platform: x11
- GPU: NVIDIA TITAN Xp, NVIDIA proprietary driver 550.163.01
- GL: ANGLE on OpenGL (gl=egl-angle,angle=opengl)
- Displays: two 2560x1440 monitors, scale 1

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Steps to reproduce

1. Close all Chromium processes that use the test profile.
2. Run this command:

/usr/lib/chromium/chromium --user-data-dir="$HOME/.config/chromium/test"

3. Then, run this command:

DESKTOP_STARTUP_ID=test_TIME0 \
    /usr/lib/chromium/chromium \
    --user-data-dir="$HOME/.config/chromium/test"

   The second process sends its command line to the first process and
   exits. The first process opens a new window.

4. Maximize the new window.

Actual result:

The maximized window does not repaint. It does not render the web page
correctly.

Expected result:

The window repaints at the maximized size, the same as the first window.

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Results of isolation tests

- The first window maximizes correctly.
- A window from Ctrl+N in the first process maximizes correctly.
- A window from step 3 fails.
- The fault stops when step 3 runs without DESKTOP_STARTUP_ID.
- The fault occurs with the binary /usr/lib/chromium/chromium. The
  wrapper /usr/bin/chromium is not a factor.
- Google Chrome <output of google-chrome --version> does not show the
  fault with the same steps.
- The fault stays with --disable-gpu-compositing. chrome://gpu
  confirmed "Compositing: Software only".
- The fault stays without --window-size, --window-position, and
  --new-window.
- The fault stays without the Plasma Browser Integration extension.
- The fault stays with KWin compositing suspended (Shift+Alt+F12).

Analysis

The second process forwards its startup ID to the first process. The first
process puts that ID on the new window as _NET_STARTUP_ID. The fault occurs only
on windows with a forwarded ID. This bug does not occur when the google-chrome
binary is used. It is specific to chromium.  The exact code path from the ID to
the stale frame is unknown.

Workaround

Unset DESKTOP_STARTUP_ID before the second launch.

Attachment
gpu-hw-compositing.txt: Hardware accelerated
gpu-sw-compositing.txt: Software only. Hardware acceleration disabled