Allow proto-path in the proto_library target

third_party/protobuf/proto_library.gni

 # Copyright 2014 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.
 
 # Compile a protocol buffer.
 #
 # Protobuf parameters:
 #
 #   proto_in_dir (optional)
 #       Specifies the path relative to the current BUILD.gn file where
 #       proto files are located and the directory structure of
 #       this proto library starts.
 #
 #       This option can be calculated automatically but it will raise an
 #       assertion error if any nested directories are found.
 #
 #   proto_out_dir (optional)
 #       Specifies the path suffix that output files are generated under.
 #       This path will be appended to |root_gen_dir|, but for python stubs
 #       it will be appended to |root_build_dir|/pyproto.
 #
+#   proto_path (optional)
+#       List of additional directories to find imported protos.
+#
 #   generate_python (optional, default true)
 #       Generate Python protobuf stubs.
 #
 #   generate_cc (optional, default true)
 #       Generate C++ protobuf stubs.
 #
 #   cc_generator_options (optional)
 #       List of extra flags passed to the protocol compiler.  If you need to
 #       add an EXPORT macro to a protobuf's C++ header, set the
 #       'cc_generator_options' variable with the value:
@@ skipping 197 matching lines @@
     protoc_out_dir = get_label_info(protoc_label, "root_out_dir")
     args += [
       # Wrapper should never pick a system protoc.
       # Path should be rebased because |root_build_dir| for current toolchain
       # may be different from |root_out_dir| of protoc built on host toolchain.
       "--protoc",
       "./" + rebase_path(protoc_out_dir, root_build_dir) + "/protoc",
       "--proto-in-dir",
       rebase_path(proto_in_dir, root_build_dir),
     ]
+    if (defined(invoker.proto_path)) {
+      foreach(_proto_dir, invoker.proto_path) {
+        args += [
+          "--proto-path",
+          rebase_path(_proto_dir, root_build_dir),
+        ]
+      }
+    }
 
     if (generate_cc) {
       args += [
         "--cc-out-dir",
         rel_cc_out_dir,
       ]
       if (defined(invoker.cc_generator_options)) {
         args += [
           "--cc-options",
           invoker.cc_generator_options,
@@ skipping 38 matching lines @@
       deps += [ plugin_host_label ]
     }
     if (defined(invoker.deps)) {
       # The deps may have steps that have to run before running protoc.
       deps += invoker.deps
     }
   }
 
   # Option to disable building a library in component build.
   if (defined(invoker.component_build_force_source_set) &&
-      invoker.component_build_force_source_set &&
-      is_component_build) {
+      invoker.component_build_force_source_set && is_component_build) {
     link_target_type = "source_set"
   } else {
     link_target_type = "static_library"
   }
 
   # Generated files may include other generated headers. These includes always
   # use relative paths starting at |cc_out_dir|.
   # However there is no necessity to add an additional directory, if all protos
   # are located in the same directory which is in the search path by default.
   if (has_nested_dirs) {
     config_name = "${target_name}_config"
     config(config_name) {
       include_dirs = [ cc_out_dir ]
     }
   }
 
   # Build generated protobuf stubs as libary or source set.
   target(link_target_type, target_name) {
     forward_variables_from(invoker,
                            [
                              "defines",
+                             "include_dirs",

[sdefresne, 2016/10/06 15:08:46]

I think this is incorrect as dependent target will also likely need those
include_dirs, and instead a config should be used. I'd say you probably need
instead an invoker.extra_public_config like there is a invoker.extra_configs
(see below).

[Olivier, 2016/10/06 16:36:31]

Done.

                              "testonly",
                              "visibility",
                            ])
 
     sources = get_target_outputs(":$action_name")
 
     if (defined(invoker.extra_configs)) {
       configs += invoker.extra_configs
     }
 
@@ skipping 21 matching lines @@
       ":$action_name",
     ]
 
     # This will link any libraries in the deps (the use of invoker.deps in the
     # action won't link it).
     if (defined(invoker.deps)) {
       deps += invoker.deps
     }
   }
 }