Tracing V2: Field number constants for protobuf plugin.

components/tracing/test/example_proto/test_messages.proto

Index: components/tracing/test/example_proto/test_messages.proto
diff --git a/components/tracing/test/example_proto/test_messages.proto b/components/tracing/test/example_proto/test_messages.proto
index 588ec84f9d22ed403ce43c25f79bcd6bce54cee6..ef5a0526b284f8ff94dd5ac4d6dc9c71ee4fca30 100644
--- a/components/tracing/test/example_proto/test_messages.proto
+++ b/components/tracing/test/example_proto/test_messages.proto
@@ -73,3 +73,19 @@ message NestedA {
   repeated NestedB repeated_a = 2;
   optional NestedB.NestedC super_nested = 3;
 }
+
+message CamelCaseFields {
+  // To check that any reasonable name converts to camel case correctly.
+  optional bool foo_bar_baz = 1;
+  optional bool barBaz = 2;
+  optional bool MooMoo = 3;
+  optional bool URLEncoder = 4;
+  optional bool XMap = 5;
+  optional bool UrLE_nco__der = 6;
+  optional bool __bigBang = 7;
+  optional bool U2 = 8;
+  optional bool bangBig__ = 9;
+
+  // Plugin should end up with error on this name.
+  // optional bool _ = 100;

[Primiano Tucci (use gerrit), 2016/08/05 08:52:05]

not sure what is the value of this comment here?
I'd just rip out lines 88-90

+}