reviewer comments

src/core/lib/channel/call_tracer.h

@@ -43,11 +43,7 @@ class CallTracer {
     // arguments.
     virtual void RecordSendInitialMetadata(
         grpc_metadata_batch* send_initial_metadata, uint32_t flags) = 0;
-    // TODO(yashkt): We are using gpr_atm here instead of absl::string_view
-    // since that's what the transport API uses, and performing an atomic load
-    // is unnecessary if the census tracer does not need it at present. Fix this
-    // when the transport API changes.
-    virtual void RecordOnDoneSendInitialMetadata(gpr_atm* peer_string) = 0;
+    virtual void RecordOnDoneSendInitialMetadata() = 0;
     virtual void RecordSendTrailingMetadata(
         grpc_metadata_batch* send_trailing_metadata) = 0;
     virtual void RecordSendMessage(const ByteStream& send_message) = 0;

src/cpp/ext/filters/census/open_census_call_tracer.h

@@ -33,7 +33,7 @@ class OpenCensusCallTracer : public grpc_core::CallTracer {
     void RecordSendInitialMetadata(
         grpc_metadata_batch* /* send_initial_metadata */,
         uint32_t /* flags */) override {}
-    void RecordOnDoneSendInitialMetadata(gpr_atm* /* peer_string */) override {}
+    void RecordOnDoneSendInitialMetadata() override {}
     void RecordSendTrailingMetadata(
         grpc_metadata_batch* /* send_trailing_metadata */) override {}
     void RecordSendMessage(