Prevent warnings in PacketRouterTest and PacketRouterRembTest

Change MockRtpRtcp to NiceMock<MockRtpRtcp> throughout PacketRouterTest and PacketRouterRembTest (12 tests in total), to suppress a large number of warnings which are currently ignored.

BUG=None

Review-Url: https://codereview.webrtc.org/2977533002
Cr-Original-Commit-Position: refs/heads/master@{#18946}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 6c9556e7f19bddbb38fadf22fd3b52672d0f59ed
diff --git a/modules/pacing/packet_router_unittest.cc b/modules/pacing/packet_router_unittest.cc
index d64d48d..e7f08ca 100644
--- a/modules/pacing/packet_router_unittest.cc
+++ b/modules/pacing/packet_router_unittest.cc
@@ -38,8 +38,8 @@
 };
 
 TEST_F(PacketRouterTest, TimeToSendPacket) {
-  MockRtpRtcp rtp_1;
-  MockRtpRtcp rtp_2;
+  NiceMock<MockRtpRtcp> rtp_1;
+  NiceMock<MockRtpRtcp> rtp_2;
   packet_router_->AddSendRtpModule(&rtp_1);
   packet_router_->AddSendRtpModule(&rtp_2);
 
@@ -118,10 +118,10 @@
   const uint16_t kSsrc1 = 1234;
   const uint16_t kSsrc2 = 4567;
 
-  MockRtpRtcp rtp_1;
+  NiceMock<MockRtpRtcp> rtp_1;
   EXPECT_CALL(rtp_1, RtxSendStatus()).WillOnce(Return(kRtxOff));
   EXPECT_CALL(rtp_1, SSRC()).WillRepeatedly(Return(kSsrc1));
-  MockRtpRtcp rtp_2;
+  NiceMock<MockRtpRtcp> rtp_2;
   // rtp_2 will be prioritized for padding.
   EXPECT_CALL(rtp_2, RtxSendStatus()).WillOnce(Return(kRtxRedundantPayloads));
   EXPECT_CALL(rtp_2, SSRC()).WillRepeatedly(Return(kSsrc2));
@@ -209,7 +209,7 @@
 }
 
 TEST_F(PacketRouterTest, SenderOnlyFunctionsRespectSendingMedia) {
-  MockRtpRtcp rtp;
+  NiceMock<MockRtpRtcp> rtp;
   packet_router_->AddSendRtpModule(&rtp);
   static const uint16_t kSsrc = 1234;
   EXPECT_CALL(rtp, SSRC()).WillRepeatedly(Return(kSsrc));
@@ -244,8 +244,8 @@
 }
 
 TEST_F(PacketRouterTest, SendTransportFeedback) {
-  MockRtpRtcp rtp_1;
-  MockRtpRtcp rtp_2;
+  NiceMock<MockRtpRtcp> rtp_1;
+  NiceMock<MockRtpRtcp> rtp_2;
   packet_router_->AddSendRtpModule(&rtp_1);
   packet_router_->AddReceiveRtpModule(&rtp_2);
 
@@ -260,8 +260,8 @@
 
 TEST(PacketRouterRembTest, PreferSendModuleOverReceiveModule) {
   rtc::ScopedFakeClock clock;
-  MockRtpRtcp rtp_recv;
-  MockRtpRtcp rtp_send;
+  NiceMock<MockRtpRtcp> rtp_recv;
+  NiceMock<MockRtpRtcp> rtp_send;
   PacketRouter packet_router;
 
   EXPECT_CALL(rtp_recv, SetREMBStatus(true)).Times(1);
@@ -298,7 +298,7 @@
 
 TEST(PacketRouterRembTest, LowerEstimateToSendRemb) {
   rtc::ScopedFakeClock clock;
-  MockRtpRtcp rtp;
+  NiceMock<MockRtpRtcp> rtp;
   PacketRouter packet_router;
 
   EXPECT_CALL(rtp, SetREMBStatus(true)).Times(1);
@@ -327,7 +327,7 @@
 
 TEST(PacketRouterRembTest, VerifyIncreasingAndDecreasing) {
   rtc::ScopedFakeClock clock;
-  MockRtpRtcp rtp;
+  NiceMock<MockRtpRtcp> rtp;
   PacketRouter packet_router;
   packet_router.AddSendRtpModule(&rtp);
 
@@ -353,7 +353,7 @@
 
 TEST(PacketRouterRembTest, NoRembForIncreasedBitrate) {
   rtc::ScopedFakeClock clock;
-  MockRtpRtcp rtp;
+  NiceMock<MockRtpRtcp> rtp;
   PacketRouter packet_router;
   packet_router.AddSendRtpModule(&rtp);
 
@@ -382,8 +382,8 @@
 
 TEST(PacketRouterRembTest, ChangeSendRtpModule) {
   rtc::ScopedFakeClock clock;
-  MockRtpRtcp rtp_send;
-  MockRtpRtcp rtp_recv;
+  NiceMock<MockRtpRtcp> rtp_send;
+  NiceMock<MockRtpRtcp> rtp_recv;
   PacketRouter packet_router;
   packet_router.AddSendRtpModule(&rtp_send);
   packet_router.AddReceiveRtpModule(&rtp_recv);
@@ -421,7 +421,7 @@
 
 TEST(PacketRouterRembTest, OnlyOneRembForRepeatedOnReceiveBitrateChanged) {
   rtc::ScopedFakeClock clock;
-  MockRtpRtcp rtp;
+  NiceMock<MockRtpRtcp> rtp;
   PacketRouter packet_router;
   packet_router.AddSendRtpModule(&rtp);
 
@@ -451,7 +451,7 @@
 // packet on this one.
 TEST(PacketRouterRembTest, NoSendingRtpModule) {
   rtc::ScopedFakeClock clock;
-  MockRtpRtcp rtp;
+  NiceMock<MockRtpRtcp> rtp;
   PacketRouter packet_router;
 
   EXPECT_CALL(rtp, SetREMBStatus(true)).Times(1);