Add FEC producer fuzzing and a unittest for one of the issues found.

webrtc/modules/rtp_rtcp/source/producer_fec_unittest.cc

Index: webrtc/modules/rtp_rtcp/source/producer_fec_unittest.cc
diff --git a/webrtc/modules/rtp_rtcp/source/producer_fec_unittest.cc b/webrtc/modules/rtp_rtcp/source/producer_fec_unittest.cc
index 683b951f1e343195fad1dadfa8c02483c59fffca..7943a1682c2d3c0d05940390f93538992efcff83 100644
--- a/webrtc/modules/rtp_rtcp/source/producer_fec_unittest.cc
+++ b/webrtc/modules/rtp_rtcp/source/producer_fec_unittest.cc
@@ -54,6 +54,26 @@ class ProducerFecTest : public ::testing::Test {
   FrameGenerator* generator_;
 };
 
+TEST_F(ProducerFecTest, FuzzOneInput) {
+  uint8_t data[] = {
+      0xf9, 0x36, 0x70, 0xc2, 0xfb, 0x28, 0x21, 0x21, 0x47, 0x3b, 0x36, 0x70,
+      0xca, 0xcf, 0xff, 0x21, 0x21, 0x45, 0x3b, 0xb6, 0x2a, 0x27, 0xd6, 0x3a,
+      0xa2, 0x27, 0x21, 0x5c, 0x3a, 0x49, 0x9b, 0x1b, 0x29, 0x84, 0x3a, 0x3a,
+      0x27, 0x54, 0x58, 0x3b, 0x28, 0xf4, 0x28, 0x27, 0x3b, 0x21, 0x3b, 0x3a,
+      0xcb, 0xc0, 0xc7, 0x29, 0x21, 0x76, 0xe6, 0x28, 0x7d, 0x97, 0x2a, 0x28,
+      0x7d, 0x28, 0x97, 0x2a, 0x29, 0x64, 0x3b, 0x1d, 0x7d, 0x56, 0xc7, 0x21,
+      0xd9, 0x12, 0x55, 0xa5, 0x28, 0x7d, 0x97, 0x2a, 0x28, 0x7d, 0x28, 0x97,
+      0x2a, 0x29, 0x64, 0x3b, 0x1d, 0x7d, 0x56, 0xc7, 0x5,  0xd9, 0x12, 0x79,
+      0x55, 0xa5, 0x56, 0xfe, 0x3a, 0x3,  0x37, 0x3b, 0x3a, 0x2a, 0x2a, 0xc7,
+      0x2c, 0x3a, 0xd1, 0xa2, 0x2a, 0x90, 0x2c, 0x21, 0x2a, 0x3b, 0x28, 0x8b,
+      0xfc, 0x3b, 0x46, 0x3b, 0xa2, 0x3b, 0x3b, 0x2a, 0x3b, 0x3b, 0x28, 0x29,
+      0xe,  0x3a, 0x2a, 0xa2, 0x46, 0x8b, 0x28, 0xff, 0x29, 0x29, 0x1,  0x8f,
+      0x9,  0x74, 0x57, 0x2a, 0x34, 0x3b, 0x3b, 0x3,  0xf0, 0x87, 0x3b, 0xfc,
+      0x5e, 0x29, 0x3b, 0x5c, 0x1a, 0xf8, 0x28, 0xcd, 0xe3, 0x98, 0x84, 0x7f,
+      0x87, 0x5f, 0x3a, 0x64, 0x1f, 0x28, 0x3b, 0x1d, 0x7d, 0x96, 0xf0, 0xc7};
+  FuzzOneInput(data, sizeof(data));

[pbos-webrtc, 2015/12/11 13:31:45]

Could you unpack this test to have the actual meaning of the data? If you change
the fuzzer in any way you lose test coverage now.

Also it confuses me that this test even links with FuzzOneInput right now? I
don't think the test name makes sense either. Is this test case for a large
sequence-number gap? If so do that? :)

[stefan-webrtc, 2015/12/11 14:26:26]

Done.

+}
+
 TEST_F(ProducerFecTest, OneFrameFec) {
   // The number of media packets (|kNumPackets|), number of frames (one for
   // this test), and the protection factor (|params->fec_rate|) are set to make