Remove QuicConnection's RetransmittableOnWireAlarm because it was replaced with the PingAlarm.

gfe-relnote: n/a (Dead code removal)
PiperOrigin-RevId: 246132311
Change-Id: I231aecdc25d0fe10f2a144a9a5b8debd89b19703

quic/core/quic_connection.cc

diff --git a/quic/core/quic_connection.cc b/quic/core/quic_connection.cc
index 1fc69e1..aa7b55a 100644
--- a/quic/core/quic_connection.cc
+++ b/quic/core/quic_connection.cc
@@ -181,21 +181,6 @@
   QuicConnection* connection_;
 };
 
-class RetransmittableOnWireAlarmDelegate : public QuicAlarm::Delegate {
- public:
-  explicit RetransmittableOnWireAlarmDelegate(QuicConnection* connection)
-      : connection_(connection) {}
-  RetransmittableOnWireAlarmDelegate(
-      const RetransmittableOnWireAlarmDelegate&) = delete;
-  RetransmittableOnWireAlarmDelegate& operator=(
-      const RetransmittableOnWireAlarmDelegate&) = delete;
-
-  void OnAlarm() override { connection_->OnPingTimeout(); }
-
- private:
-  QuicConnection* connection_;
-};
-
 class ProcessUndecryptablePacketsAlarmDelegate : public QuicAlarm::Delegate {
  public:
   explicit ProcessUndecryptablePacketsAlarmDelegate(QuicConnection* connection)
@@ -3224,12 +3209,13 @@
 
 void QuicConnection::SetPingAlarm() {
   if (perspective_ == Perspective::IS_SERVER) {
-    // Only clients send pings.
+    // Only clients send pings to avoid NATs from timing out.
     return;
   }
   if (!visitor_->ShouldKeepConnectionAlive()) {
     ping_alarm_->Cancel();
-    // Don't send a ping unless there are open streams.
+    // Don't send a ping unless the application (ie: HTTP/3) says to, usually
+    // because it is expecting a response from the server.
     return;
   }
   if (retransmittable_on_wire_timeout_.IsInfinite() ||

quic/core/quic_connection.h

diff --git a/quic/core/quic_connection.h b/quic/core/quic_connection.h
index 3173ee3..cf534ed 100644
--- a/quic/core/quic_connection.h
+++ b/quic/core/quic_connection.h
@@ -836,8 +836,6 @@
 
   bool session_decides_what_to_write() const;
 
-  void SetRetransmittableOnWireAlarm();
-
   // Sets the current per-packet options for the connection. The QuicConnection
   // does not take ownership of |options|; |options| must live for as long as
   // the QuicConnection is in use.