diff --git a/quic/core/quic_connection.cc b/quic/core/quic_connection.cc
index 0aa7a4d..a19eae0 100644
--- a/quic/core/quic_connection.cc
+++ b/quic/core/quic_connection.cc
@@ -1943,6 +1943,8 @@
   // discard_previous_one_rtt_keys_alarm_ hasn't fired yet, cancel it since the
   // old keys would already be discarded.
   discard_previous_one_rtt_keys_alarm_->Cancel();
+
+  visitor_->OnKeyUpdate(reason);
 }
 
 void QuicConnection::OnDecryptedFirstPacketInKeyPhase() {
diff --git a/quic/core/quic_connection.h b/quic/core/quic_connection.h
index 2fc8c8a..73c6706 100644
--- a/quic/core/quic_connection.h
+++ b/quic/core/quic_connection.h
@@ -196,6 +196,9 @@
   // Called when a packet of ENCRYPTION_HANDSHAKE gets sent.
   virtual void OnHandshakePacketSent() = 0;
 
+  // Called when a key update has occurred.
+  virtual void OnKeyUpdate(KeyUpdateReason reason) = 0;
+
   // Called to generate a decrypter for the next key phase. Each call should
   // generate the key for phase n+1.
   virtual std::unique_ptr<QuicDecrypter>
diff --git a/quic/core/quic_connection_test.cc b/quic/core/quic_connection_test.cc
index 483ddb1..fd84b30 100644
--- a/quic/core/quic_connection_test.cc
+++ b/quic/core/quic_connection_test.cc
@@ -12096,6 +12096,7 @@
   EXPECT_CALL(visitor_, CreateCurrentOneRttEncrypter()).WillOnce([]() {
     return std::make_unique<TaggingEncrypter>(0x02);
   });
+  EXPECT_CALL(visitor_, OnKeyUpdate(KeyUpdateReason::kLocalForTests));
   EXPECT_TRUE(connection_.InitiateKeyUpdate(KeyUpdateReason::kLocalForTests));
   // discard_previous_keys_alarm_ should not be set until a packet from the new
   // key phase has been received. (The alarm that was set above should be
@@ -12132,6 +12133,7 @@
   EXPECT_CALL(visitor_, CreateCurrentOneRttEncrypter()).WillOnce([]() {
     return std::make_unique<TaggingEncrypter>(0x03);
   });
+  EXPECT_CALL(visitor_, OnKeyUpdate(KeyUpdateReason::kLocalForTests));
   EXPECT_TRUE(connection_.InitiateKeyUpdate(KeyUpdateReason::kLocalForTests));
 
   // Pretend that peer accepts the key update.
@@ -12166,6 +12168,7 @@
   EXPECT_CALL(visitor_, CreateCurrentOneRttEncrypter()).WillOnce([]() {
     return std::make_unique<TaggingEncrypter>(0x04);
   });
+  EXPECT_CALL(visitor_, OnKeyUpdate(KeyUpdateReason::kLocalForTests));
   EXPECT_TRUE(connection_.InitiateKeyUpdate(KeyUpdateReason::kLocalForTests));
   EXPECT_FALSE(connection_.GetDiscardPreviousOneRttKeysAlarm()->IsSet());
 }
@@ -12230,6 +12233,8 @@
           .WillOnce([current_tag]() {
             return std::make_unique<TaggingEncrypter>(current_tag);
           });
+      EXPECT_CALL(visitor_,
+                  OnKeyUpdate(KeyUpdateReason::kLocalKeyUpdateLimitOverride));
     }
     // Send packet.
     QuicPacketNumber last_packet;
diff --git a/quic/core/quic_session.h b/quic/core/quic_session.h
index 8fca9bd..d162d59 100644
--- a/quic/core/quic_session.h
+++ b/quic/core/quic_session.h
@@ -137,6 +137,7 @@
   void OnPacketDecrypted(EncryptionLevel level) override;
   void OnOneRttPacketAcknowledged() override;
   void OnHandshakePacketSent() override;
+  void OnKeyUpdate(KeyUpdateReason /*reason*/) override {}
   std::unique_ptr<QuicDecrypter> AdvanceKeysAndCreateCurrentOneRttDecrypter()
       override;
   std::unique_ptr<QuicEncrypter> CreateCurrentOneRttEncrypter() override;
diff --git a/quic/test_tools/quic_test_utils.h b/quic/test_tools/quic_test_utils.h
index e577174..cff9d1a 100644
--- a/quic/test_tools/quic_test_utils.h
+++ b/quic/test_tools/quic_test_utils.h
@@ -581,6 +581,7 @@
   MOCK_METHOD(void, OnPacketDecrypted, (EncryptionLevel), (override));
   MOCK_METHOD(void, OnOneRttPacketAcknowledged, (), (override));
   MOCK_METHOD(void, OnHandshakePacketSent, (), (override));
+  MOCK_METHOD(void, OnKeyUpdate, (KeyUpdateReason), (override));
   MOCK_METHOD(std::unique_ptr<QuicDecrypter>,
               AdvanceKeysAndCreateCurrentOneRttDecrypter,
               (),
diff --git a/quic/test_tools/simulator/quic_endpoint.h b/quic/test_tools/simulator/quic_endpoint.h
index 7f5bef2..681cd33 100644
--- a/quic/test_tools/simulator/quic_endpoint.h
+++ b/quic/test_tools/simulator/quic_endpoint.h
@@ -94,6 +94,7 @@
   void OnPacketDecrypted(EncryptionLevel /*level*/) override {}
   void OnOneRttPacketAcknowledged() override {}
   void OnHandshakePacketSent() override {}
+  void OnKeyUpdate(KeyUpdateReason /*reason*/) override {}
   std::unique_ptr<QuicDecrypter> AdvanceKeysAndCreateCurrentOneRttDecrypter()
       override {
     return nullptr;