[Cast] Fix RtcpParser to parse negative playout delay deltas in receiver reports.

media/cast/net/rtcp/rtcp_utility_unittest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/memory/scoped_ptr.h"
 #include "base/test/simple_test_tick_clock.h"
 #include "media/cast/cast_environment.h"
 #include "media/cast/net/cast_transport_defines.h"
 #include "media/cast/net/rtcp/rtcp_utility.h"
 #include "media/cast/net/rtcp/test_rtcp_packet_builder.h"
@@ skipping 349 matching lines @@
   p.AddReceiverEventLog(kLostPacketId2, PACKET_RECEIVED, kTimeDelayMs);
 
   RtcpParser parser(kSourceSsrc, kSenderSsrc);
   EXPECT_TRUE(parser.Parse(p.Reader()));
   ExpectReceiverLog(parser, receiver_log);
 }
 
 TEST_F(RtcpParserTest, InjectReceiverReportWithReceiverLogVerificationMulti) {
   static const uint32 kTimeBaseMs = 12345678;
   static const uint32 kTimeDelayMs = 10;
-  static const uint32 kDelayDeltaMs = 123;
+  static const int kDelayDeltaMs = 123;  // To be varied for every frame.
   base::SimpleTestTickClock testing_clock;
   testing_clock.Advance(base::TimeDelta::FromMilliseconds(kTimeBaseMs));
 
   RtcpReceiverLogMessage receiver_log;
 
   for (int j = 0; j < 100; ++j) {
     RtcpReceiverFrameLogMessage frame_log(kRtpTimestamp);
     RtcpReceiverEventLogMessage event_log;
     event_log.type = FRAME_ACK_SENT;
     event_log.event_timestamp = testing_clock.NowTicks();
-    event_log.delay_delta = base::TimeDelta::FromMilliseconds(kDelayDeltaMs);
+    event_log.delay_delta =
+        base::TimeDelta::FromMilliseconds((j - 50) * kDelayDeltaMs);
     frame_log.event_log_messages_.push_back(event_log);
     receiver_log.push_back(frame_log);
     testing_clock.Advance(base::TimeDelta::FromMilliseconds(kTimeDelayMs));
   }
 
   TestRtcpPacketBuilder p;
   p.AddRr(kSenderSsrc, 1);
   p.AddRb(kSourceSsrc);
   p.AddReceiverLog(kSenderSsrc);
   for (int i = 0; i < 100; ++i) {
     p.AddReceiverFrameLog(kRtpTimestamp, 1, kTimeBaseMs + i * kTimeDelayMs);
-    p.AddReceiverEventLog(kDelayDeltaMs, FRAME_ACK_SENT, 0);
+    const int delay = (i - 50) * kDelayDeltaMs;
+    p.AddReceiverEventLog(static_cast<uint16>(delay), FRAME_ACK_SENT, 0);
   }
 
   RtcpParser parser(kSourceSsrc, kSenderSsrc);
   EXPECT_TRUE(parser.Parse(p.Reader()));
   ExpectReceiverLog(parser, receiver_log);
 }
 
 }  // namespace cast
 }  // namespace media