Remove an unnecessary QUIC_BUG that causes unit tests to flake.

Bug: https://bugs.chromium.org/p/chromium/issues/detail?id=1351746
PiperOrigin-RevId: 480592828

quiche/quic/core/io/quic_all_event_loops_test.cc

diff --git a/quiche/quic/core/io/quic_all_event_loops_test.cc b/quiche/quic/core/io/quic_all_event_loops_test.cc
index 16eb344..ed62824 100644
--- a/quiche/quic/core/io/quic_all_event_loops_test.cc
+++ b/quiche/quic/core/io/quic_all_event_loops_test.cc
@@ -419,5 +419,22 @@
   loop_->RunEventLoopOnce(QuicTime::Delta::FromMilliseconds(-1));
 }
 
+TEST_P(QuicEventLoopFactoryTest, ScheduleAlarmInPastFromInsideAlarm) {
+  constexpr auto kAlarmTimeout = QuicTime::Delta::FromMilliseconds(20);
+  auto [alarm1_ptr, delegate1] = CreateAlarm();
+  auto [alarm2_ptr, delegate2] = CreateAlarm();
+
+  alarm1_ptr->Set(clock_.Now() - kAlarmTimeout);
+  EXPECT_CALL(*delegate1, OnAlarm())
+      .WillOnce([&, alarm2_unowned = alarm2_ptr.get()]() {
+        alarm2_unowned->Set(clock_.Now() - 2 * kAlarmTimeout);
+      });
+  bool fired = false;
+  EXPECT_CALL(*delegate2, OnAlarm()).WillOnce([&]() { fired = true; });
+
+  RunEventLoopUntil([&]() { return fired; },
+                    QuicTime::Delta::FromMilliseconds(100));
+}
+
 }  // namespace
 }  // namespace quic::test

quiche/quic/core/io/quic_poll_event_loop.cc

diff --git a/quiche/quic/core/io/quic_poll_event_loop.cc b/quiche/quic/core/io/quic_poll_event_loop.cc
index 1c90be5..f56635f 100644
--- a/quiche/quic/core/io/quic_poll_event_loop.cc
+++ b/quiche/quic/core/io/quic_poll_event_loop.cc
@@ -99,12 +99,9 @@
   }
   QuicTime end_time = std::min(now + default_timeout, alarms_.begin()->first);
   if (end_time < now) {
-    // Since we call ProcessAlarmsUpTo() right before this, this should never
-    // happen.
-    QUIC_BUG(Newest alarm is in the past)
-        << "now " << now.ToDebuggingValue()
-        << ", end_time: " << end_time.ToDebuggingValue()
-        << ", default timeout: " << default_timeout;
+    // We only run a single pass of processing alarm callbacks per
+    // RunEventLoopOnce() call.  If an alarm schedules another alarm in the past
+    // while in the callback, this will happen.
     return QuicTime::Delta::Zero();
   }
   return end_time - now;