GN: fix bootstrap

//base/trace_event/memory_dump_manager.cc now needs the generated
//base/debug/debugging_flags.h file.

Generating that file when building manually with ninja fixes
bootstrapping.

R=brettw@chromium.org
BUG=

Review-Url: https://codereview.chromium.org/1929403002
Cr-Original-Commit-Position: refs/heads/master@{#391055}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: c86fe9393074586d43d9b83ee2866cfa201ad7d4
1 file changed
tree: 74eebc65ec2610c2fa37c0af42d281fa496153c4
  1. tools/