Tracing V2: Import support for protobuf plugin.

components/tracing/test/example_proto/library.proto

Index: components/tracing/test/example_proto/library.proto
diff --git a/components/tracing/test/example_proto/library.proto b/components/tracing/test/example_proto/library.proto
new file mode 100644
index 0000000000000000000000000000000000000000..04f019ea72c6244ec9322aa6ed104a3ccf9ac75d
--- /dev/null
+++ b/components/tracing/test/example_proto/library.proto
@@ -0,0 +1,16 @@
+// Copyright 2016 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.
+
+syntax = "proto2";
+package foo.bar;
+
+import public "library_internals/galaxies.proto";
+
+message TransgalacticMessage {
+  optional Galaxy origin_galaxy = 1;
+  optional string origin_planet = 2;
+  optional Galaxy destination_galaxy = 3;
+  optional string destination_planet = 4;
+  optional bytes proto_message = 5;
+}