Improve error messages in extensions/docs/build.py .

chrome/common/extensions/docs/build/build.py

 #!/usr/bin/python
 # Copyright (c) 2009 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.
 
 """Docbuilder for extension docs."""
 
 import os
 import os.path
 import shutil
@@ skipping 112 matching lines @@
   for loc in search_locations:
     if os.path.isfile(loc):
       return loc
 
   raise Exception ("Could not find test_shell executable\n" +
                    "**test_shell may need to be built**\n" +
                    "Searched: \n" + "\n".join(search_locations) + "\n" +
                    "To specify a path to test_shell use --test-shell-path")
 
 def GetAPIModuleNames():
-  contents = open(_extension_api_json, 'r').read();
-  extension_api = json.loads(contents, encoding="ASCII")
-  return set( module['namespace'].encode() for module in extension_api)
+  try:
+    contents = open(_extension_api_json, 'r').read()
+  except IOError, msg:
+    raise Exception("Failed to read the file that defines the extensions API.  "
+                    "The specific error was: %s." % msg)
+
+  try:
+    extension_api = json.loads(contents, encoding="ASCII")
+  except ValueError, msg:
+    raise Exception("File %s has a syntax error: %s" %
+                    (_extension_api_json, msg))
+
+  return set(module['namespace'].encode() for module in extension_api)
 
 def GetStaticFileNames():
   static_files = os.listdir(_static_dir)
   return set(os.path.splitext(file)[0]
              for file in static_files
              if file.endswith(".html"))
 
 def main():
   parser = OptionParser()
   parser.add_option("--test-shell-path", dest="test_shell_path")
@@ skipping 33 matching lines @@
   # and the os.remove will fail with a "Permission denied".
   time.sleep(1);
   debug_log = os.path.normpath(_build_dir + "/" + "debug.log");
   if (os.path.isfile(debug_log)):
     os.remove(debug_log)
 
   return 0;
 
 if __name__ == '__main__':
   sys.exit(main())