modules/video_coding refactorings

The main purpose was the interface-> include rename, but other files
were also moved, eliminating the "main" dir.

To avoid breaking downstream, the "interface" directories were copied
into a new "video_coding/include" dir. The old headers got pragma
warnings added about deprecation (a very short deprecation since I plan
to remove them as soon downstream is updated).

Other files also moved:
video_coding/main/source -> video_coding
video_coding/main/test -> video_coding/test

BUG=webrtc:5095
TESTED=Passing compile-trybots with --clobber flag:
git cl try --clobber --bot=win_compile_rel --bot=linux_compile_rel --bot=android_compile_rel --bot=mac_compile_rel --bot=ios_rel --bot=linux_gn_rel --bot=win_x64_gn_rel --bot=mac_x64_gn_rel --bot=android_gn_rel -m tryserver.webrtc

R=stefan@webrtc.org, tommi@webrtc.org

Review URL: https://codereview.webrtc.org/1417283007 .

Cr-Commit-Position: refs/heads/master@{#10694}
diff --git a/webrtc/modules/video_coding/decoding_state_unittest.cc b/webrtc/modules/video_coding/decoding_state_unittest.cc
new file mode 100644
index 0000000..5f5d0d3
--- /dev/null
+++ b/webrtc/modules/video_coding/decoding_state_unittest.cc
@@ -0,0 +1,699 @@
+/*
+ *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include <string.h>
+
+#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/modules/include/module_common_types.h"
+#include "webrtc/modules/video_coding/decoding_state.h"
+#include "webrtc/modules/video_coding/frame_buffer.h"
+#include "webrtc/modules/video_coding/jitter_buffer_common.h"
+#include "webrtc/modules/video_coding/packet.h"
+
+namespace webrtc {
+
+TEST(TestDecodingState, Sanity) {
+  VCMDecodingState dec_state;
+  dec_state.Reset();
+  EXPECT_TRUE(dec_state.in_initial_state());
+  EXPECT_TRUE(dec_state.full_sync());
+}
+
+TEST(TestDecodingState, FrameContinuity) {
+  VCMDecodingState dec_state;
+  // Check that makes decision based on correct method.
+  VCMFrameBuffer frame;
+  VCMFrameBuffer frame_key;
+  VCMPacket packet;
+  packet.isFirstPacket = true;
+  packet.timestamp = 1;
+  packet.seqNum = 0xffff;
+  packet.frameType = kVideoFrameDelta;
+  packet.codecSpecificHeader.codec = kRtpVideoVp8;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 0x007F;
+  FrameData frame_data;
+  frame_data.rtt_ms = 0;
+  frame_data.rolling_average_packets_per_frame = -1;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  // Always start with a key frame.
+  dec_state.Reset();
+  EXPECT_FALSE(dec_state.ContinuousFrame(&frame));
+  packet.frameType = kVideoFrameKey;
+  EXPECT_LE(0, frame_key.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame_key));
+  dec_state.SetState(&frame);
+  frame.Reset();
+  packet.frameType = kVideoFrameDelta;
+  // Use pictureId
+  packet.isFirstPacket = false;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 0x0002;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_FALSE(dec_state.ContinuousFrame(&frame));
+  frame.Reset();
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 0;
+  packet.seqNum = 10;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+
+  // Use sequence numbers.
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = kNoPictureId;
+  frame.Reset();
+  packet.seqNum = dec_state.sequence_num() - 1u;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_FALSE(dec_state.ContinuousFrame(&frame));
+  frame.Reset();
+  packet.seqNum = dec_state.sequence_num() + 1u;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  // Insert another packet to this frame
+  packet.seqNum++;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  // Verify wrap.
+  EXPECT_LE(dec_state.sequence_num(), 0xffff);
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+
+  // Insert packet with temporal info.
+  dec_state.Reset();
+  frame.Reset();
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 0;
+  packet.seqNum = 1;
+  packet.timestamp = 1;
+  EXPECT_TRUE(dec_state.full_sync());
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  dec_state.SetState(&frame);
+  EXPECT_TRUE(dec_state.full_sync());
+  frame.Reset();
+  // 1 layer up - still good.
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx = 1;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 1;
+  packet.seqNum = 2;
+  packet.timestamp = 2;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+  EXPECT_TRUE(dec_state.full_sync());
+  frame.Reset();
+  // Lost non-base layer packet => should update sync parameter.
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx = 3;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 3;
+  packet.seqNum = 4;
+  packet.timestamp = 4;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_FALSE(dec_state.ContinuousFrame(&frame));
+  // Now insert the next non-base layer (belonging to a next tl0PicId).
+  frame.Reset();
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx = 1;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx = 2;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 4;
+  packet.seqNum = 5;
+  packet.timestamp = 5;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  // Checking continuity and not updating the state - this should not trigger
+  // an update of sync state.
+  EXPECT_FALSE(dec_state.ContinuousFrame(&frame));
+  EXPECT_TRUE(dec_state.full_sync());
+  // Next base layer (dropped interim non-base layers) - should update sync.
+  frame.Reset();
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx = 1;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 5;
+  packet.seqNum = 6;
+  packet.timestamp = 6;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+  EXPECT_FALSE(dec_state.full_sync());
+
+  // Check wrap for temporal layers.
+  frame.Reset();
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx = 0x00FF;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 6;
+  packet.seqNum = 7;
+  packet.timestamp = 7;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  dec_state.SetState(&frame);
+  EXPECT_FALSE(dec_state.full_sync());
+  frame.Reset();
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx = 0x0000;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 7;
+  packet.seqNum = 8;
+  packet.timestamp = 8;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  // The current frame is not continuous
+  dec_state.SetState(&frame);
+  EXPECT_FALSE(dec_state.ContinuousFrame(&frame));
+}
+
+TEST(TestDecodingState, UpdateOldPacket) {
+  VCMDecodingState dec_state;
+  // Update only if zero size and newer than previous.
+  // Should only update if the timeStamp match.
+  VCMFrameBuffer frame;
+  VCMPacket packet;
+  packet.timestamp = 1;
+  packet.seqNum = 1;
+  packet.frameType = kVideoFrameDelta;
+  FrameData frame_data;
+  frame_data.rtt_ms = 0;
+  frame_data.rolling_average_packets_per_frame = -1;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  dec_state.SetState(&frame);
+  EXPECT_EQ(dec_state.sequence_num(), 1);
+  // Insert an empty packet that does not belong to the same frame.
+  // => Sequence num should be the same.
+  packet.timestamp = 2;
+  dec_state.UpdateOldPacket(&packet);
+  EXPECT_EQ(dec_state.sequence_num(), 1);
+  // Now insert empty packet belonging to the same frame.
+  packet.timestamp = 1;
+  packet.seqNum = 2;
+  packet.frameType = kEmptyFrame;
+  packet.sizeBytes = 0;
+  dec_state.UpdateOldPacket(&packet);
+  EXPECT_EQ(dec_state.sequence_num(), 2);
+  // Now insert delta packet belonging to the same frame.
+  packet.timestamp = 1;
+  packet.seqNum = 3;
+  packet.frameType = kVideoFrameDelta;
+  packet.sizeBytes = 1400;
+  dec_state.UpdateOldPacket(&packet);
+  EXPECT_EQ(dec_state.sequence_num(), 3);
+  // Insert a packet belonging to an older timestamp - should not update the
+  // sequence number.
+  packet.timestamp = 0;
+  packet.seqNum = 4;
+  packet.frameType = kEmptyFrame;
+  packet.sizeBytes = 0;
+  dec_state.UpdateOldPacket(&packet);
+  EXPECT_EQ(dec_state.sequence_num(), 3);
+}
+
+TEST(TestDecodingState, MultiLayerBehavior) {
+  // Identify sync/non-sync when more than one layer.
+  VCMDecodingState dec_state;
+  // Identify packets belonging to old frames/packets.
+  // Set state for current frames.
+  // tl0PicIdx 0, temporal id 0.
+  VCMFrameBuffer frame;
+  VCMPacket packet;
+  packet.frameType = kVideoFrameDelta;
+  packet.codecSpecificHeader.codec = kRtpVideoVp8;
+  packet.timestamp = 0;
+  packet.seqNum = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 0;
+  FrameData frame_data;
+  frame_data.rtt_ms = 0;
+  frame_data.rolling_average_packets_per_frame = -1;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  dec_state.SetState(&frame);
+  // tl0PicIdx 0, temporal id 1.
+  frame.Reset();
+  packet.timestamp = 1;
+  packet.seqNum = 1;
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx = 1;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 1;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+  EXPECT_TRUE(dec_state.full_sync());
+  // Lost tl0PicIdx 0, temporal id 2.
+  // Insert tl0PicIdx 0, temporal id 3.
+  frame.Reset();
+  packet.timestamp = 3;
+  packet.seqNum = 3;
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx = 3;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 3;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_FALSE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+  EXPECT_FALSE(dec_state.full_sync());
+  // Insert next base layer
+  frame.Reset();
+  packet.timestamp = 4;
+  packet.seqNum = 4;
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx = 1;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 4;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+  EXPECT_FALSE(dec_state.full_sync());
+  // Insert key frame - should update sync value.
+  // A key frame is always a base layer.
+  frame.Reset();
+  packet.frameType = kVideoFrameKey;
+  packet.isFirstPacket = 1;
+  packet.timestamp = 5;
+  packet.seqNum = 5;
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx = 2;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 5;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+  EXPECT_TRUE(dec_state.full_sync());
+  // After sync, a continuous PictureId is required
+  // (continuous base layer is not enough )
+  frame.Reset();
+  packet.frameType = kVideoFrameDelta;
+  packet.timestamp = 6;
+  packet.seqNum = 6;
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx = 3;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 6;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  EXPECT_TRUE(dec_state.full_sync());
+  frame.Reset();
+  packet.frameType = kVideoFrameDelta;
+  packet.isFirstPacket = 1;
+  packet.timestamp = 8;
+  packet.seqNum = 8;
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx = 4;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 8;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_FALSE(dec_state.ContinuousFrame(&frame));
+  EXPECT_TRUE(dec_state.full_sync());
+  dec_state.SetState(&frame);
+  EXPECT_FALSE(dec_state.full_sync());
+
+  // Insert a non-ref frame - should update sync value.
+  frame.Reset();
+  packet.frameType = kVideoFrameDelta;
+  packet.isFirstPacket = 1;
+  packet.timestamp = 9;
+  packet.seqNum = 9;
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx = 4;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx = 2;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 9;
+  packet.codecSpecificHeader.codecHeader.VP8.layerSync = true;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  dec_state.SetState(&frame);
+  EXPECT_TRUE(dec_state.full_sync());
+
+  // The following test will verify the sync flag behavior after a loss.
+  // Create the following pattern:
+  // Update base layer, lose packet 1 (sync flag on, layer 2), insert packet 3
+  // (sync flag on, layer 2) check continuity and sync flag after inserting
+  // packet 2 (sync flag on, layer 1).
+  // Base layer.
+  frame.Reset();
+  dec_state.Reset();
+  packet.frameType = kVideoFrameDelta;
+  packet.isFirstPacket = 1;
+  packet.markerBit = 1;
+  packet.timestamp = 0;
+  packet.seqNum = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.layerSync = false;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  dec_state.SetState(&frame);
+  EXPECT_TRUE(dec_state.full_sync());
+  // Layer 2 - 2 packets (insert one, lose one).
+  frame.Reset();
+  packet.frameType = kVideoFrameDelta;
+  packet.isFirstPacket = 1;
+  packet.markerBit = 0;
+  packet.timestamp = 1;
+  packet.seqNum = 1;
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx = 2;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 1;
+  packet.codecSpecificHeader.codecHeader.VP8.layerSync = true;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  // Layer 1
+  frame.Reset();
+  packet.frameType = kVideoFrameDelta;
+  packet.isFirstPacket = 1;
+  packet.markerBit = 1;
+  packet.timestamp = 2;
+  packet.seqNum = 3;
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx = 1;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 2;
+  packet.codecSpecificHeader.codecHeader.VP8.layerSync = true;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_FALSE(dec_state.ContinuousFrame(&frame));
+  EXPECT_TRUE(dec_state.full_sync());
+}
+
+TEST(TestDecodingState, DiscontinuousPicIdContinuousSeqNum) {
+  VCMDecodingState dec_state;
+  VCMFrameBuffer frame;
+  VCMPacket packet;
+  frame.Reset();
+  packet.frameType = kVideoFrameKey;
+  packet.codecSpecificHeader.codec = kRtpVideoVp8;
+  packet.timestamp = 0;
+  packet.seqNum = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 0;
+  FrameData frame_data;
+  frame_data.rtt_ms = 0;
+  frame_data.rolling_average_packets_per_frame = -1;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  dec_state.SetState(&frame);
+  EXPECT_TRUE(dec_state.full_sync());
+
+  // Continuous sequence number but discontinuous picture id. This implies a
+  // a loss and we have to fall back to only decoding the base layer.
+  frame.Reset();
+  packet.frameType = kVideoFrameDelta;
+  packet.timestamp += 3000;
+  ++packet.seqNum;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx = 1;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 2;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_FALSE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+  EXPECT_FALSE(dec_state.full_sync());
+}
+
+TEST(TestDecodingState, OldInput) {
+  VCMDecodingState dec_state;
+  // Identify packets belonging to old frames/packets.
+  // Set state for current frames.
+  VCMFrameBuffer frame;
+  VCMPacket packet;
+  packet.timestamp = 10;
+  packet.seqNum = 1;
+  FrameData frame_data;
+  frame_data.rtt_ms = 0;
+  frame_data.rolling_average_packets_per_frame = -1;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  dec_state.SetState(&frame);
+  packet.timestamp = 9;
+  EXPECT_TRUE(dec_state.IsOldPacket(&packet));
+  // Check for old frame
+  frame.Reset();
+  frame.InsertPacket(packet, 0, kNoErrors, frame_data);
+  EXPECT_TRUE(dec_state.IsOldFrame(&frame));
+}
+
+TEST(TestDecodingState, PictureIdRepeat) {
+  VCMDecodingState dec_state;
+  VCMFrameBuffer frame;
+  VCMPacket packet;
+  packet.frameType = kVideoFrameDelta;
+  packet.codecSpecificHeader.codec = kRtpVideoVp8;
+  packet.timestamp = 0;
+  packet.seqNum = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx = 0;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId = 0;
+  FrameData frame_data;
+  frame_data.rtt_ms = 0;
+  frame_data.rolling_average_packets_per_frame = -1;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  dec_state.SetState(&frame);
+  // tl0PicIdx 0, temporal id 1.
+  frame.Reset();
+  ++packet.timestamp;
+  ++packet.seqNum;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx++;
+  packet.codecSpecificHeader.codecHeader.VP8.pictureId++;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  frame.Reset();
+  // Testing only gap in tl0PicIdx when tl0PicIdx in continuous.
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx += 3;
+  packet.codecSpecificHeader.codecHeader.VP8.temporalIdx++;
+  packet.codecSpecificHeader.codecHeader.VP8.tl0PicIdx = 1;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_FALSE(dec_state.ContinuousFrame(&frame));
+}
+
+TEST(TestDecodingState, FrameContinuityFlexibleModeKeyFrame) {
+  VCMDecodingState dec_state;
+  VCMFrameBuffer frame;
+  VCMPacket packet;
+  packet.isFirstPacket = true;
+  packet.timestamp = 1;
+  packet.seqNum = 0xffff;
+  uint8_t data[] = "I need a data pointer for this test!";
+  packet.sizeBytes = sizeof(data);
+  packet.dataPtr = data;
+  packet.codecSpecificHeader.codec = kRtpVideoVp9;
+
+  RTPVideoHeaderVP9& vp9_hdr = packet.codecSpecificHeader.codecHeader.VP9;
+  vp9_hdr.picture_id = 10;
+  vp9_hdr.flexible_mode = true;
+
+  FrameData frame_data;
+  frame_data.rtt_ms = 0;
+  frame_data.rolling_average_packets_per_frame = -1;
+
+  // Key frame as first frame
+  packet.frameType = kVideoFrameKey;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+
+  // Key frame again
+  vp9_hdr.picture_id = 11;
+  frame.Reset();
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+
+  // Ref to 11, continuous
+  frame.Reset();
+  packet.frameType = kVideoFrameDelta;
+  vp9_hdr.picture_id = 12;
+  vp9_hdr.num_ref_pics = 1;
+  vp9_hdr.pid_diff[0] = 1;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+}
+
+TEST(TestDecodingState, FrameContinuityFlexibleModeOutOfOrderFrames) {
+  VCMDecodingState dec_state;
+  VCMFrameBuffer frame;
+  VCMPacket packet;
+  packet.isFirstPacket = true;
+  packet.timestamp = 1;
+  packet.seqNum = 0xffff;
+  uint8_t data[] = "I need a data pointer for this test!";
+  packet.sizeBytes = sizeof(data);
+  packet.dataPtr = data;
+  packet.codecSpecificHeader.codec = kRtpVideoVp9;
+
+  RTPVideoHeaderVP9& vp9_hdr = packet.codecSpecificHeader.codecHeader.VP9;
+  vp9_hdr.picture_id = 10;
+  vp9_hdr.flexible_mode = true;
+
+  FrameData frame_data;
+  frame_data.rtt_ms = 0;
+  frame_data.rolling_average_packets_per_frame = -1;
+
+  // Key frame as first frame
+  packet.frameType = kVideoFrameKey;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+
+  // Ref to 10, continuous
+  frame.Reset();
+  packet.frameType = kVideoFrameDelta;
+  vp9_hdr.picture_id = 15;
+  vp9_hdr.num_ref_pics = 1;
+  vp9_hdr.pid_diff[0] = 5;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+
+  // Out of order, last id 15, this id 12, ref to 10, continuous
+  frame.Reset();
+  vp9_hdr.picture_id = 12;
+  vp9_hdr.pid_diff[0] = 2;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+
+  // Ref 10, 12, 15, continuous
+  frame.Reset();
+  vp9_hdr.picture_id = 20;
+  vp9_hdr.num_ref_pics = 3;
+  vp9_hdr.pid_diff[0] = 10;
+  vp9_hdr.pid_diff[1] = 8;
+  vp9_hdr.pid_diff[2] = 5;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+}
+
+TEST(TestDecodingState, FrameContinuityFlexibleModeGeneral) {
+  VCMDecodingState dec_state;
+  VCMFrameBuffer frame;
+  VCMPacket packet;
+  packet.isFirstPacket = true;
+  packet.timestamp = 1;
+  packet.seqNum = 0xffff;
+  uint8_t data[] = "I need a data pointer for this test!";
+  packet.sizeBytes = sizeof(data);
+  packet.dataPtr = data;
+  packet.codecSpecificHeader.codec = kRtpVideoVp9;
+
+  RTPVideoHeaderVP9& vp9_hdr = packet.codecSpecificHeader.codecHeader.VP9;
+  vp9_hdr.picture_id = 10;
+  vp9_hdr.flexible_mode = true;
+
+  FrameData frame_data;
+  frame_data.rtt_ms = 0;
+  frame_data.rolling_average_packets_per_frame = -1;
+
+  // Key frame as first frame
+  packet.frameType = kVideoFrameKey;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+
+  // Delta frame as first frame
+  frame.Reset();
+  packet.frameType = kVideoFrameDelta;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_FALSE(dec_state.ContinuousFrame(&frame));
+
+  // Key frame then delta frame
+  frame.Reset();
+  packet.frameType = kVideoFrameKey;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  dec_state.SetState(&frame);
+  frame.Reset();
+  packet.frameType = kVideoFrameDelta;
+  vp9_hdr.num_ref_pics = 1;
+  vp9_hdr.picture_id = 15;
+  vp9_hdr.pid_diff[0] = 5;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+
+  // Ref to 11, not continuous
+  frame.Reset();
+  vp9_hdr.picture_id = 16;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_FALSE(dec_state.ContinuousFrame(&frame));
+
+  // Ref to 15, continuous
+  frame.Reset();
+  vp9_hdr.picture_id = 16;
+  vp9_hdr.pid_diff[0] = 1;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+
+  // Ref to 11 and 15, not continuous
+  frame.Reset();
+  vp9_hdr.picture_id = 20;
+  vp9_hdr.num_ref_pics = 2;
+  vp9_hdr.pid_diff[0] = 9;
+  vp9_hdr.pid_diff[1] = 5;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_FALSE(dec_state.ContinuousFrame(&frame));
+
+  // Ref to 10, 15 and 16, continuous
+  frame.Reset();
+  vp9_hdr.picture_id = 22;
+  vp9_hdr.num_ref_pics = 3;
+  vp9_hdr.pid_diff[0] = 12;
+  vp9_hdr.pid_diff[1] = 7;
+  vp9_hdr.pid_diff[2] = 6;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+
+  // Key Frame, continuous
+  frame.Reset();
+  packet.frameType = kVideoFrameKey;
+  vp9_hdr.picture_id = VCMDecodingState::kFrameDecodedLength - 2;
+  vp9_hdr.num_ref_pics = 0;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+
+  // Frame at last index, ref to KF, continuous
+  frame.Reset();
+  packet.frameType = kVideoFrameDelta;
+  vp9_hdr.picture_id = VCMDecodingState::kFrameDecodedLength - 1;
+  vp9_hdr.num_ref_pics = 1;
+  vp9_hdr.pid_diff[0] = 1;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+
+  // Frame after wrapping buffer length, ref to last index, continuous
+  frame.Reset();
+  vp9_hdr.picture_id = 0;
+  vp9_hdr.num_ref_pics = 1;
+  vp9_hdr.pid_diff[0] = 1;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+
+  // Frame after wrapping start frame, ref to 0, continuous
+  frame.Reset();
+  vp9_hdr.picture_id = 20;
+  vp9_hdr.num_ref_pics = 1;
+  vp9_hdr.pid_diff[0] = 20;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+
+  // Frame after wrapping start frame, ref to 10, not continuous
+  frame.Reset();
+  vp9_hdr.picture_id = 23;
+  vp9_hdr.num_ref_pics = 1;
+  vp9_hdr.pid_diff[0] = 13;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_FALSE(dec_state.ContinuousFrame(&frame));
+
+  // Key frame, continuous
+  frame.Reset();
+  packet.frameType = kVideoFrameKey;
+  vp9_hdr.picture_id = 25;
+  vp9_hdr.num_ref_pics = 0;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+
+  // Ref to KF, continuous
+  frame.Reset();
+  packet.frameType = kVideoFrameDelta;
+  vp9_hdr.picture_id = 26;
+  vp9_hdr.num_ref_pics = 1;
+  vp9_hdr.pid_diff[0] = 1;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_TRUE(dec_state.ContinuousFrame(&frame));
+  dec_state.SetState(&frame);
+
+  // Ref to frame previous to KF, not continuous
+  frame.Reset();
+  vp9_hdr.picture_id = 30;
+  vp9_hdr.num_ref_pics = 1;
+  vp9_hdr.pid_diff[0] = 30;
+  EXPECT_LE(0, frame.InsertPacket(packet, 0, kNoErrors, frame_data));
+  EXPECT_FALSE(dec_state.ContinuousFrame(&frame));
+}
+
+}  // namespace webrtc