linux_me2me_host.py: Quit gnome-session properly

When the gnome-session process is killed, it can cause the service
restart to halt at times. This change tries to stop the gnome-session
using gnome-session-quit instead.

Bug: chromium:1291247
Change-Id: Iee4763ab86fd7bf73518dfeae2a8ace8950e47cc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4192107
Reviewed-by: Lambros Lambrou <lambroslambrou@chromium.org>
Auto-Submit: Salman Malik <salmanmalik@chromium.org>
Commit-Queue: Salman Malik <salmanmalik@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1096363}

remoting/host/linux/linux_me2me_host.py

@@ -159,9 +159,12 @@
 # wayland compositor/server for clients to connect to.
 RUNTIME_DIR_TEMPLATE = "/run/user/%s"
 
-# Binary name for the gnome-session.
+# Binary name for `gnome-session`.
 GNOME_SESSION = "gnome-session"
 
+# Binary name for `gnome-session-quit`.
+GNOME_SESSION_QUIT = "gnome-session-quit"
+
 # Globals needed by the atexit cleanup() handler.
 g_desktop = None
 g_host_hash = hashlib.md5(socket.gethostname().encode()).hexdigest()
@@ -933,6 +936,39 @@ def _wait_for_setup_before_host_launch(self):
     return self._wait_for_wayland_compositor_running()
 
   def cleanup(self):
+    if self.host_proc is not None:
+      logging.info("Sending SIGTERM to host proc (pid=%s)", self.host_proc.pid)
+      try:
+        psutil_proc = psutil.Process(self.host_proc.pid)
+        psutil_proc.terminate()
+
+        # Use a short timeout, to avoid delaying service shutdown if the
+        # process refuses to die for some reason.
+        psutil_proc.wait(timeout=10)
+      except psutil.TimeoutExpired:
+        logging.error("Timed out - sending SIGKILL")
+        psutil_proc.kill()
+      except psutil.Error:
+        logging.error("Error terminating process")
+      self.host_proc = None
+
+    # We currently only support gnome-session (which is currently managed)
+    # by CRD itself.
+    logging.info("Executing %s" % GNOME_SESSION_QUIT)
+    if shutil.which(GNOME_SESSION_QUIT):
+      cleanup_proc = subprocess.Popen(
+        [GNOME_SESSION_QUIT, "--force", "--no-prompt"],
+        stdout=subprocess.PIPE,
+        stderr=subprocess.PIPE,
+        env=self.child_env)
+      stdout, stderr = cleanup_proc.communicate()
+      if stderr:
+        logging.error("Failed to execute %s:\n%s" %
+                      (GNOME_SESSION_QUIT, stderr))
+      self.session_proc = None
+    else:
+      logging.warning("No %s found on the system" % GNOME_SESSION_QUIT)
+
     super(WaylandDesktop, self).cleanup()
     if self._wayland_socket:
       full_socket_path = os.path.join(self.runtime_dir, self._wayland_socket)