Fix incorrectly resolved conflict, and add error message for missing sources.

ppapi/generators/idl_parser.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.
 
 """ Parser for PPAPI IDL """
 
 #
 # IDL Parser
 #
@@ skipping 1000 matching lines @@
     filenames = []
     srcroot = GetOption('srcroot')
     dirs = default_dirs
     if GetOption('include_private'):
       dirs += ['private']
     for dirname in dirs:
       srcdir = os.path.join(srcroot, dirname, '*.idl')
       srcdir = os.path.normpath(srcdir)
       filenames += sorted(glob.glob(srcdir))
 
+  if not filenames:
+    ErrOut.Log('No sources provided.')
+
   for filename in filenames:
     filenode = parser.ParseFile(filename)
     filenodes.append(filenode)
 
   ast = IDLAst(filenodes)
   if GetOption('dump_tree'): ast.Dump(0)
 
   Lint(ast)
   return ast
 
@@ skipping 14 matching lines @@
   ast = ParseFiles(filenames)
   errs = ast.GetProperty('ERRORS')
   if errs:
     ErrOut.Log('Found %d error(s).' % errs);
   InfoOut.Log("%d files processed." % len(filenames))
   return errs
 
 
 if __name__ == '__main__':
   sys.exit(Main(sys.argv[1:]))