Implement periodic bandwidth probing in application-limited region.

webrtc/modules/pacing/mock/mock_paced_sender.h

Index: webrtc/modules/pacing/mock/mock_paced_sender.h
diff --git a/webrtc/modules/pacing/mock/mock_paced_sender.h b/webrtc/modules/pacing/mock/mock_paced_sender.h
index b83032c24af183511a95ebbfe9bd6306888d05d2..eacc334e0a478db1e57d799f6eab89e2f800ff0a 100644
--- a/webrtc/modules/pacing/mock/mock_paced_sender.h
+++ b/webrtc/modules/pacing/mock/mock_paced_sender.h
@@ -33,6 +33,8 @@ class MockPacedSender : public PacedSender {
   MOCK_CONST_METHOD0(QueueInMs, int64_t());
   MOCK_CONST_METHOD0(QueueInPackets, int());
   MOCK_CONST_METHOD0(ExpectedQueueTimeMs, int64_t());
+  MOCK_CONST_METHOD0(GetApplicationLimitedRegionStartTime,
+                     rtc::Optional<int64_t>());
 };
 
 }  // namespace webrtc