Tool added to extract network traffic annotations.

third_party/protobuf/BUILD.gn

Index: third_party/protobuf/BUILD.gn
diff --git a/third_party/protobuf/BUILD.gn b/third_party/protobuf/BUILD.gn
index 84c916a651e8347ae93661d3056337fe4a060e7d..23efe6079dbeb1c935143e02cfa9131bce17a911 100644
--- a/third_party/protobuf/BUILD.gn
+++ b/third_party/protobuf/BUILD.gn
@@ -177,7 +177,13 @@ component("protobuf_lite") {
 # into that category. Do not use in Chrome code.
 static_library("protobuf_full") {
   # Prevent people from depending on this outside our file.
-  visibility = [ ":*" ]
+  visibility = [
+    ":*",
+
+    # The traffic_annotation tool is not part of Chrome itself, and needs to
+    # parse human-readable protobufs.
+    "//tools/traffic_annotation/*",
+  ]
 
   sources = protobuf_lite_sources
   sources += [