perfetto-ui: Slices with the same name should be the same colour
perfetto-ui: Slices with the same name should be the same colour

Userspace slices were previously coloured in a gradient, depending on the depth.
Because depth is already visible, changing the colour of the slice based on it's name.
Any slices with the same name should be the same colour.

Bug:140092592
Change-Id: Iba052d36ba83b87351d01b017accf170d7555164
google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto