proto_zero_plugin [NOT FOR REVIEW].

components/tracing/proto_zero_test/mock_messages.proto

+syntax = "proto2";
+
+package foo.bar;
+
+enum SmallEnum {
+  TO_BE = 1;
+  NOT_TO_BE = 0;
+}
+
+enum SignedEnum {
+  POSITIVE = 1;
+  NEUTRAL = 0;
+  NEGATIVE = -1;
+}
+
+enum BigEnum {
+  BEGIN = 10;
+  END = 100500;
+}
+
+message EveryField {
+  optional int32 field_int32 = 1;
+  optional int64 field_int64 = 2;
+  optional uint32 field_uint32 = 3;
+  optional uint64 field_uint64 = 4;
+  optional sint32 field_sint32 = 5;
+  optional sint64 field_sint64 = 6;
+  optional fixed32 field_fixed32 = 7;
+  optional fixed64 field_fixed64 = 8;
+  optional sfixed32 field_sfixed32 = 9;
+  optional sfixed64 field_sfixed64 = 10;
+  optional float field_float = 11;
+  optional double field_double = 12;
+  optional bool field_bool = 13;
+
+  optional SmallEnum small_enum = 51;
+  optional SignedEnum signed_enum = 52;
+  optional BigEnum big_enum = 53;
+
+  optional string field_string = 500;
+  optional bytes field_bytes = 505;
+
+  enum NestedEnum {
+    PING = 1;
+    PONG = 2;
+  }
+  optional NestedEnum nested_enum = 600;
+
+  repeated int32 repeated_int32 = 999;
+}
+
+message NestedA {
+  message NestedB {
+    message NestedC {
+      optional int32 value_c = 1;
+    }
+    optional NestedC value_b = 1;
+  }
+  repeated NestedB repeated_a = 2;
+}