CrOS: Convert MediaTransferProtocolDaemonClient to use protobufs.

build/protoc.gypi

Index: build/protoc.gypi
===================================================================
--- build/protoc.gypi	(revision 155895)
+++ build/protoc.gypi	(working copy)
@@ -39,9 +39,12 @@
 
 {
   'variables': {
+    'protoc_wrapper': '<(DEPTH)/tools/protoc_wrapper/protoc_wrapper.py',
     'protoc': '<(PRODUCT_DIR)/<(EXECUTABLE_PREFIX)protoc<(EXECUTABLE_SUFFIX)',
     'cc_dir': '<(SHARED_INTERMEDIATE_DIR)/protoc_out/<(proto_out_dir)',
     'py_dir': '<(PRODUCT_DIR)/pyproto/<(proto_out_dir)',
+    'cc_extra%': '',

[Ryan Sleevi, 2012/09/12 19:47:32]

Please add documentation about cc_extra and cc_include to the above comment.

I'd also suggest renaming cc_extra to be more indicative of its purpose (unless
this is what protoc also calls it?)

+    'cc_include%': '',
     'proto_in_dir%': '.',
   },
   'rules': [
@@ -49,6 +52,7 @@
       'rule_name': 'genproto',
       'extension': 'proto',
       'inputs': [
+        '<(protoc_wrapper)',
         '<(protoc)',
       ],
       'outputs': [
@@ -57,6 +61,9 @@
         '<(cc_dir)/<(RULE_INPUT_ROOT).pb.h',
       ],
       'action': [
+        'python',
+        '<(protoc_wrapper)',
+        '<(cc_include)' ':' '<(cc_dir)/<(RULE_INPUT_ROOT).pb.h',

[Ryan Sleevi, 2012/09/12 19:47:32]

If no 'cc_include' is specified, this expands to an argument of :foo/bar.pb.h

Unfortunately, because this is a GYPI that is included by multiple targets, it's
not "cleanly" possible to use nested variables to create some 'cc_include_flag'
meta-variable.

Further, Nico's been working on supporting ':' in filenames in Ninja, so I'm not
sure using ':' as a delimiter is wise.

Finally, concatenating strings like GYP in this way is not really a 'supported'
or 'good' way, it just happens to work as a side-effect of how Python's parsing
things. The correct form would be:
'<(cc_include):<(cc_dir)/<(RULE_INPUT_ROOT).pb.h' (although, like I said, using
':' isn't that good here. This string concatenation note also applies to line
74.

My recommendation, for those reasons, is to make the cc_include and the pb.h
flagged arguments to protoc_wrapper. eg:

--include_file (path_or_null)
--protobuf_file (path)
-- (used by the Python script to say 'ignore all that follows')
(protoc command to execute and remaining args)

         '<(protoc)',
         # Using the --arg val form (instead of --arg=val) allows gyp's msvs rule
         # generation to correct 'val' which is a path.
@@ -64,8 +71,8 @@
         # Naively you'd use <(RULE_INPUT_PATH) here, but protoc requires
         # --proto_path is a strict prefix of the path given as an argument.
         '<(proto_in_dir)/<(RULE_INPUT_ROOT)<(RULE_INPUT_EXT)',
-        '--cpp_out','<(cc_dir)',
-        '--python_out','<(py_dir)',
+        '--cpp_out', '<(cc_extra)' '<(cc_dir)',
+        '--python_out', '<(py_dir)',
         ],
       'msvs_cygwin_shell': 0,
       'message': 'Generating C++ and Python code from <(RULE_INPUT_PATH)',
@@ -78,6 +85,7 @@
   ],
   'include_dirs': [
     '<(SHARED_INTERMEDIATE_DIR)/protoc_out',
+    '<(DEPTH)',
   ],
   'direct_dependent_settings': {
     'include_dirs': [