Improve trace_inputs.py to output a format easy to convert to gypi.

testing/xvfb.py

 #!/usr/bin/env python
 # 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.
 
 """Runs the test with xvfb on linux. Runs the test normally on other platforms.
 
 For simplicity in gyp targets, this script just runs the test normal on
 non-linux platforms.
 """
@@ skipping 46 matching lines @@
 
 
 def wait_for_xvfb(xdisplaycheck, env):
   """Waits for xvfb to be fully initialized by using xdisplaycheck."""
   try:
     subprocess.check_call(
         [xdisplaycheck],
         stdout=subprocess.PIPE,
         stderr=subprocess.STDOUT,
         env=env)
+  except OSError:
+    print >> sys.stderr, 'Failed to load %s with cwd=%s' % (
+        xdisplaycheck, os.getcwd())
+    return False
   except subprocess.CalledProcessError:
-    print >> sys.stderr, 'Xvfb failed to load properly.'
+    print >> sys.stderr, (
+        'Xvfb failed to load properly while trying to run %s' % xdisplaycheck)
     return False
   return True
 
 
 def run_executable(cmd, build_dir, env):
   """Runs an executable within a xvfb buffer on linux or normally on other
   platforms.
 
   Requires that both xvfb and icewm are installed on linux.
   """
@@ skipping 20 matching lines @@
 def main():
   if len(sys.argv) < 3:
     print >> sys.stderr, (
         'Usage: xvfb.py [path to build_dir] [command args...]')
     return 2
   return run_executable(sys.argv[2:], sys.argv[1], os.environ.copy())
 
 
 if __name__ == "__main__":
   sys.exit(main())