Fix QuicSession.ConnectionDuration

What went wrong: Previously handshake_completion_timestamp_ was only stamped at OnOneRttKeysAvailable().
But from the base method in the shared code, this method is only called with TLS QUIC. Thus this histogram is broken for gQUIC.

connection_timing_.connect_end works for both QUIC versions.

Change-Id: Ie3b60a8d4169b3a6ccc32b79877290275f26bbc8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2358369
Auto-Submit: Renjie Tang <renjietang@chromium.org>
Reviewed-by: David Schinazi <dschinazi@chromium.org>
Commit-Queue: David Schinazi <dschinazi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#798410}

net/quic/quic_chromium_client_session.cc

@@ -862,7 +862,6 @@ QuicChromiumClientSession::QuicChromiumClientSession(
       max_allowed_push_id_(max_allowed_push_id),
       attempted_zero_rtt_(false),
       num_pings_sent_(0),
-      handshake_completion_timestamp_(base::TimeTicks()),
       push_promise_index_(std::move(push_promise_index)) {
   // Make sure connection migration and goaway on path degrading are not turned
   // on at the same time.
@@ -1611,7 +1610,6 @@ void QuicChromiumClientSession::OnOneRttKeysAvailable() {
 
   OnCryptoHandshakeComplete();
   LogZeroRttStats();
-  handshake_completion_timestamp_ = tick_clock_->NowTicks();
   quic::QuicSpdySession::OnOneRttKeysAvailable();
 }
 
@@ -1800,7 +1798,7 @@ void QuicChromiumClientSession::OnConnectionClosed(
     UMA_HISTOGRAM_COUNTS_1000("Net.QuicSession.NumPingsSent", num_pings_sent_);
     UMA_HISTOGRAM_LONG_TIMES_100(
         "Net.QuicSession.ConnectionDuration",
-        tick_clock_->NowTicks() - handshake_completion_timestamp_);
+        tick_clock_->NowTicks() - connect_timing_.connect_end);
   } else {
     if (error == quic::QUIC_PUBLIC_RESET) {
       RecordHandshakeFailureReason(HANDSHAKE_FAILURE_PUBLIC_RESET);

net/quic/quic_chromium_client_session.h

@@ -929,8 +929,6 @@ class NET_EXPORT_PRIVATE QuicChromiumClientSession
 
   size_t num_pings_sent_;
 
-  base::TimeTicks handshake_completion_timestamp_;
-
   std::unique_ptr<quic::QuicClientPushPromiseIndex> push_promise_index_;
 
   base::WeakPtrFactory<QuicChromiumClientSession> weak_factory_{this};