The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ddb9a7684d76165a63b8d383b5b67701ea13cc93

commit ddb9a7684d76165a63b8d383b5b67701ea13cc93
Author: James Cook <jamescook@chromium.org>
Date: Tue Aug 14 20:44:57 2018

Collapse ash::TouchHudDebug and ash::TouchObserverHUD

The former is the only subclass of the latter. The other subclass was
removed when we switched the --show-taps feature to using the
tap_visualizer mojo UI app.

Pure clean up, no functional changes.

Bug:  873264 
Test: ash_unittests, manual test of --ash-touch-hud then Ctrl-Alt-I
Change-Id: I5e81f57655a69ee6b4f33e4ed42d27285481a83c
Reviewed-on: https://chromium-review.googlesource.com/1173254
Reviewed-by: Mohsen Izadi <mohsen@chromium.org>
Commit-Queue: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583021}
[modify] https://crrev.com/ddb9a7684d76165a63b8d383b5b67701ea13cc93/ash/BUILD.gn
[modify] https://crrev.com/ddb9a7684d76165a63b8d383b5b67701ea13cc93/ash/accelerators/accelerator_controller.cc
[modify] https://crrev.com/ddb9a7684d76165a63b8d383b5b67701ea13cc93/ash/root_window_controller.cc
[modify] https://crrev.com/ddb9a7684d76165a63b8d383b5b67701ea13cc93/ash/root_window_controller.h
[delete] https://crrev.com/a37f17593eb309fbbd5e4be7bfea3e95d6a4bd1c/ash/touch/touch_hud_debug.cc
[delete] https://crrev.com/a37f17593eb309fbbd5e4be7bfea3e95d6a4bd1c/ash/touch/touch_hud_debug.h
[modify] https://crrev.com/ddb9a7684d76165a63b8d383b5b67701ea13cc93/ash/touch/touch_observer_hud.cc
[modify] https://crrev.com/ddb9a7684d76165a63b8d383b5b67701ea13cc93/ash/touch/touch_observer_hud.h
[modify] https://crrev.com/ddb9a7684d76165a63b8d383b5b67701ea13cc93/ash/touch/touch_observer_hud_unittest.cc
[modify] https://crrev.com/ddb9a7684d76165a63b8d383b5b67701ea13cc93/chrome/browser/chromeos/system_logs/DEPS
[modify] https://crrev.com/ddb9a7684d76165a63b8d383b5b67701ea13cc93/chrome/browser/chromeos/system_logs/touch_log_source.cc