Implemented a new sequence number unwrapper in sequence_number_util.h.

webrtc/rtc_base/mod_ops_unittest.cc

Index: webrtc/rtc_base/mod_ops_unittest.cc
diff --git a/webrtc/rtc_base/mod_ops_unittest.cc b/webrtc/rtc_base/mod_ops_unittest.cc
index c375305e2d3c15e1821f342c5a701db0dc5b6c23..d39ea061b6f5724af88e055641b6d1bf249f3155 100644
--- a/webrtc/rtc_base/mod_ops_unittest.cc
+++ b/webrtc/rtc_base/mod_ops_unittest.cc
@@ -87,6 +87,14 @@ TEST_F(TestModOps, ForwardDiff) {
   }
 }
 
+TEST_F(TestModOps, ForwardDiffWithDivisor) {
+  ASSERT_EQ(122, (ForwardDiff<uint8_t, 123>(0, 122)));
+  ASSERT_EQ(0, (ForwardDiff<uint8_t, 123>(122, 122)));
+  ASSERT_EQ(122, (ForwardDiff<uint8_t, 123>(1, 0)));
+  ASSERT_EQ(0, (ForwardDiff<uint8_t, 123>(0, 0)));
+  ASSERT_EQ(1, (ForwardDiff<uint8_t, 123>(122, 0)));
+}
+
 TEST_F(TestModOps, ReverseDiff) {
   ASSERT_EQ(0u, ReverseDiff(4711u, 4711u));
 
@@ -106,6 +114,14 @@ TEST_F(TestModOps, ReverseDiff) {
   }
 }
 
+TEST_F(TestModOps, ReverseDiffWithDivisor) {
+  ASSERT_EQ(1, (ReverseDiff<uint8_t, 123>(0, 122)));
+  ASSERT_EQ(0, (ReverseDiff<uint8_t, 123>(122, 122)));
+  ASSERT_EQ(1, (ReverseDiff<uint8_t, 123>(1, 0)));
+  ASSERT_EQ(0, (ReverseDiff<uint8_t, 123>(0, 0)));
+  ASSERT_EQ(122, (ReverseDiff<uint8_t, 123>(122, 0)));
+}
+
 TEST_F(TestModOps, MinDiff) {
   for (uint16_t i = 0; i < 256; ++i) {
     ASSERT_EQ(0, MinDiff<uint8_t>(i, i));