Fix for fuzzer bug.

webrtc/modules/audio_coding/neteq/decision_logic_normal.cc

Index: webrtc/modules/audio_coding/neteq/decision_logic_normal.cc
diff --git a/webrtc/modules/audio_coding/neteq/decision_logic_normal.cc b/webrtc/modules/audio_coding/neteq/decision_logic_normal.cc
index c271bd969df2c4a5065334f2794edde776524ad7..c5f25707586c009856b598a692e944ddc551ba20 100644
--- a/webrtc/modules/audio_coding/neteq/decision_logic_normal.cc
+++ b/webrtc/modules/audio_coding/neteq/decision_logic_normal.cc
@@ -97,14 +97,17 @@ Operations DecisionLogicNormal::CngOperation(Modes prev_mode,
       available_timestamp);
   int32_t optimal_level_samp = static_cast<int32_t>(
       (delay_manager_->TargetLevel() * packet_length_samples_) >> 8);
-  int32_t excess_waiting_time_samp = -timestamp_diff - optimal_level_samp;
+  const int64_t excess_waiting_time_samp =
+      -static_cast<int64_t>(timestamp_diff) - optimal_level_samp;
 
   if (excess_waiting_time_samp > optimal_level_samp / 2) {
     // The waiting time for this packet will be longer than 1.5
     // times the wanted buffer delay. Apply fast-forward to cut the
     // waiting time down to the optimal.
-    noise_fast_forward_ += excess_waiting_time_samp;
-    timestamp_diff += excess_waiting_time_samp;
+    noise_fast_forward_ = rtc::dchecked_cast<size_t>(noise_fast_forward_ +
+                                                     excess_waiting_time_samp);
+    timestamp_diff =
+        rtc::saturated_cast<int32_t>(timestamp_diff + excess_waiting_time_samp);
   }
 
   if (timestamp_diff < 0 && prev_mode == kModeRfc3389Cng) {