Reorder protobuf compiler command line arguments.

Attempt to chase non-repoducible bug. CL crrev.com/2239383002 has
changed a command line for protoc and there are rare occasional
crashes on Win32. It could be because of some bug in protoc's parser.
This change restores a command line like before the suspecting CL
only for the most common case with only one proto file in a library.

BUG=644525

Review-Url: https://codereview.chromium.org/2324823002
Cr-Commit-Position: refs/heads/master@{#417544}

tools/protoc_wrapper/protoc_wrapper.py

@@ -96,15 +96,15 @@ def main(argv):
   options = parser.parse_args()
 
   proto_dir = os.path.relpath(options.proto_in_dir)
-  protoc_cmd = [
-    os.path.realpath(options.protoc),
-    "--proto_path", proto_dir
-  ]
+  protoc_cmd = [os.path.realpath(options.protoc)]
 
   protos = options.protos
   headers = []
   VerifyProtoNames(protos)
 
+  if options.py_out_dir:
+    protoc_cmd += ["--python_out", options.py_out_dir]
+
   if options.cc_out_dir:
     cc_out_dir = options.cc_out_dir
     cc_options = FormatGeneratorOptions(options.cc_options)
@@ -113,9 +113,6 @@ def main(argv):
       stripped_name = StripProtoExtension(filename)
       headers.append(os.path.join(cc_out_dir, stripped_name + ".pb.h"))
 
-  if options.py_out_dir:
-    protoc_cmd += ["--python_out", options.py_out_dir]
-
   if options.plugin_out_dir:
     plugin_options = FormatGeneratorOptions(options.plugin_options)
     protoc_cmd += [
@@ -123,6 +120,7 @@ def main(argv):
       "--plugin_out", plugin_options + options.plugin_out_dir
     ]
 
+  protoc_cmd += ["--proto_path", proto_dir]
   protoc_cmd += [os.path.join(proto_dir, name) for name in protos]
   ret = subprocess.call(protoc_cmd)
   if ret != 0: