perfetto: refactor and massively speed up gen_build am: b0f4019352
perfetto: refactor and massively speed up gen_build
am: b0f4019352

Change-Id: I3f9d857bdcb619d956fd1c8937613f9beaa10f74

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