Check for valid slice in UpdateThreadDeltasForSliceId.
Check for valid slice in UpdateThreadDeltasForSliceId.

Bug: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=23959
Change-Id: Ia3f0d4a2be796426091c45caac8030e8ee3d96cc
google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto