Re-enable tests that failed under Linux_Msan.

Fixed in latest libvpx roll.
Keep EndToEndTest.TransportSeqNumOnAudioAndVideo disabled on
Win_DrMemory for now as it seems to time-out/too slow.

TBR=stefan@webrtc.org, kjellander@webrtc.org
BUG=webrtc:5402
NOTRY=True

Review URL: https://codereview.webrtc.org/1577313003

Cr-Original-Commit-Position: refs/heads/master@{#11240}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 8432e1f4b84f79c4eea3a0820f4c4a83c267ef80
diff --git a/video/video_send_stream_tests.cc b/video/video_send_stream_tests.cc
index efdee19..4cf9274 100644
--- a/video/video_send_stream_tests.cc
+++ b/video/video_send_stream_tests.cc
@@ -2146,9 +2146,6 @@
   TestVp9NonFlexMode(kNumTemporalLayers, kNumSpatialLayers);
 }
 
-#if !defined(MEMORY_SANITIZER)
-// Fails under MemorySanitizer:
-// See https://code.google.com/p/webrtc/issues/detail?id=5402.
 TEST_F(VideoSendStreamTest, Vp9NonFlexMode_2Tl2SLayers) {
   const uint8_t kNumTemporalLayers = 2;
   const uint8_t kNumSpatialLayers = 2;
@@ -2160,7 +2157,6 @@
   const uint8_t kNumSpatialLayers = 2;
   TestVp9NonFlexMode(kNumTemporalLayers, kNumSpatialLayers);
 }
-#endif
 
 void VideoSendStreamTest::TestVp9NonFlexMode(uint8_t num_temporal_layers,
                                              uint8_t num_spatial_layers) {