On ChromeOS, brltty is run as its own user instead of root.
It has group memberships to allow it access to the tty.
This patch changes an open call so that /dev/tty0 is only opened for
writing (it just issues some ioctl calls on the device), which is necessary
because the tty group only has write access to /dev/tty0.

--- a/Drivers/Screen/Linux/screen.c
+++ b/Drivers/Screen/Linux/screen.c
@@ -351,7 +351,7 @@
   int opened = 0;
   char *name = vtName(consoleName, vt);
   if (name) {
-    int console = openCharacterDevice(name, O_RDWR|O_NOCTTY, 4, vt);
+    int console = openCharacterDevice(name, O_WRONLY|O_NOCTTY, 4, vt);
     if (console != -1) {
       logMessage(LOG_DEBUG, "console opened: %s: fd=%d", name, console);
       closeConsole();