Fix a GPU watchdog V1 bug on X11

The GPU watchdog will not crash if we're not on the TTY of our host X11
server. But simply doing return without calling OnAcknowledge() will
stop the watchdog. Add OnAcknowledge() before return to fix this bug.

Bug: 1036444
Change-Id: I6d6ce9ebf57a4d7fa2b6f88162afa3a2cb2689d8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1977307
Commit-Queue: Maggie Chen <magchen@chromium.org>
Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#726890}

gpu/ipc/service/gpu_watchdog_thread.cc

@@ -401,6 +401,7 @@ void GpuWatchdogThreadImplV1::DeliberatelyTerminateToRecoverFromHang() {
   // Don't crash if we're not on the TTY of our host X11 server.
   int active_tty = GetActiveTTY();
   if (host_tty_ != -1 && active_tty != -1 && host_tty_ != active_tty) {
+    OnAcknowledge();
     return;
   }
 #endif