UI: Add Canary + Stable channel switch
Adds support for switching channels from the UI.
Right now switching to Canary has no effect because
there is no {canary: ...} mapping in the index.html.
However this will JustWork as we start changing the
index.
Bug: 179864115
Change-Id: I1bac996a51eecbb33bbd16c3c7c191de83b1e0e7Perfetto is a production-grade open-source stack for performance instrumentation and trace analysis. It offers services and libraries and for recording system-level and app-level traces, native + java heap profiling, a library for analyzing traces using SQL and a web-based UI to visualize and explore multi-GB traces.
See https://perfetto.dev/docs or the /docs/ directory for documentation.