Add more interesting return codes to xdisplaycheck.

tools/xdisplaycheck/xdisplaycheck.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // This is a small program that tries to connect to the X server.  It
 // continually retries until it connects or 30 seconds pass.  If it fails
 // to connect to the X server or fails to find needed functiona, it returns
 // an error code of -1.
 //
 // This is to help verify that a useful X server is available before we start
@@ skipping 66 matching lines @@
 
   fprintf(stderr, "Connected after %d retries\n", tries);
 
 #if defined(USE_AURA)
   // Check for XInput2
   int opcode, event, err;
   if (!XQueryExtension(scoped_display.display(), "XInputExtension", &opcode,
                        &event, &err)) {
     fprintf(stderr,
         "Failed to get XInputExtension on %s.\n", XDisplayName(NULL));
-    return -1;
+    return -2;
   }
 
   int major = 2, minor = 0;
   if (XIQueryVersion(scoped_display.display(), &major, &minor) == BadRequest) {
     fprintf(stderr,
         "Server does not have XInput2 on %s.\n", XDisplayName(NULL));
-    return -1;
+    return -3;
   }
 
   // Ask for the list of devices. This can cause some Xvfb to crash.
   int count = 0;
   XIDeviceInfo* devices =
       XIQueryDevice(scoped_display.display(), XIAllDevices, &count);
   if (devices)
     XIFreeDeviceInfo(devices);
 
   fprintf(stderr,
       "XInput2 verified initially sane on %s.\n", XDisplayName(NULL));
 #endif
   return 0;
 }
 
 #if defined(LEAK_SANITIZER)
 // XOpenDisplay leaks memory if it takes more than one try to connect. This
 // causes LSan bots to fail. We don't care about memory leaks in xdisplaycheck
 // anyway, so just disable LSan completely.
 // This function isn't referenced from the executable itself. Make sure it isn't
 // stripped by the linker.
 __attribute__((used))
 __attribute__((visibility("default")))
 extern "C" int __lsan_is_turned_off() { return 1; }
 #endif