Allow proto-path in the proto_library target

third_party/protobuf/proto_library.gni

Index: third_party/protobuf/proto_library.gni
diff --git a/third_party/protobuf/proto_library.gni b/third_party/protobuf/proto_library.gni
index cca81063760ce01c567c66bdd855e5c4ab6dacef..092ca525d299edb95e8c65b95804ba98febb78c4 100644
--- a/third_party/protobuf/proto_library.gni
+++ b/third_party/protobuf/proto_library.gni
@@ -19,6 +19,9 @@
 #       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.
 #
@@ -236,6 +239,14 @@ template("proto_library") {
       "--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 += [
@@ -294,8 +305,7 @@ template("proto_library") {
 
   # 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"
@@ -327,7 +337,13 @@ template("proto_library") {
       configs += invoker.extra_configs
     }
 
-    public_configs = [ "//third_party/protobuf:using_proto" ]
+    if (!defined(invoker.public_configs)) {

[sdefresne, 2016/10/06 16:44:44]

The pattern we usually use is the following:

forward_variables_from(invoker,
                       [
                         "defines",
                         "public_configs",
                         "testonly",
                         "visibility",
                       ])

if (!defined(public_configs)) {
  public_configs = []
}
public_configs += [ "//third_party/protobuf:using_proto" ]

+      public_configs = []
+    } else {
+      public_configs = invoker.public_configs
+    }
+
+    public_configs += [ "//third_party/protobuf:using_proto" ]
 
     if (generate_cc || generate_with_plugin) {
       # Not necessary if all protos are located in the same directory.