service: Remove some DCHECKs on writer {un,}registration (part 2). am: 3896bf19ac am: 373011b5bc am: 80d7ab27b8
service: Remove some DCHECKs on writer {un,}registration (part 2). am: 3896bf19ac am: 373011b5bc am: 80d7ab27b8

Change-Id: Ic4a081bfff6e1230971dffc9d2b24a58e86b3b2b

google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto