Throwing a bunch of other components on this in case this might break something. afakhry@ can we chat this week about this?

Sure.

 Issue 438865  has been merged into this issue.

 Issue 569034  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/bf2df88ff67f1b3837615d502d189775a46e4e8b

commit bf2df88ff67f1b3837615d502d189775a46e4e8b
Author: michaelpg <michaelpg@chromium.org>
Date: Tue Aug 16 22:38:31 2016

Allow remapping modifier keys to Caps Lock and Backspace

I've found no reason to disallow remapping Ctrl, Alt or Diamond to the
Caps Lock or Backspace keys. This adds them to the dropdown menus
in Options (MD Settings to come).

BUG= 608625 

Review-Url: https://codereview.chromium.org/2248163002
Cr-Commit-Position: refs/heads/master@{#412363}

[modify] https://crrev.com/bf2df88ff67f1b3837615d502d189775a46e4e8b/chrome/browser/chromeos/events/event_rewriter.cc
[modify] https://crrev.com/bf2df88ff67f1b3837615d502d189775a46e4e8b/chrome/browser/ui/webui/options/chromeos/keyboard_handler.cc
[modify] https://crrev.com/bf2df88ff67f1b3837615d502d189775a46e4e8b/chrome/common/pref_names.cc

Why do we want backspace to be remappable?

tbuckley can provide more context, but we've moved a lot of CrOS shortcuts to Search, so users who still want Search remapped now need to map some other key back to Search.

For example, I remap Search to Backspace because Backspace is too far for my taste. So why not make Backspace map to Search? (Really, why not? Most of the code to support making Backspace and Escape remappable went into the unit test[1]. I've played around with it on my samus and haven't encountered any issues with repeat, accelerators, caps lock state, etc.)

(FWIW, I was doing this long before we started changing shortcuts, and just happen to be the person who does CrOS settings... so though I have personal bias, I'm not the one who suggested or prioritized this!)

[1] https://codereview.chromium.org/2250473006/

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/168ecd71dbd357efb815c2b8380a434331d4cae7

commit 168ecd71dbd357efb815c2b8380a434331d4cae7
Author: michaelpg <michaelpg@chromium.org>
Date: Thu Aug 25 04:00:42 2016

Settings to remap Backspace and Escape keys

We can remap modifier keys in Settings, but not Backspace or Escape;
this adds settings to remap those keys and handles them in EventRewriter.

BUG= 608625 
R=kpschoedel@chromium.org,stevenjb@chromium.org,sadrul@chromium.org
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2250473006
Cr-Commit-Position: refs/heads/master@{#414303}

[modify] https://crrev.com/168ecd71dbd357efb815c2b8380a434331d4cae7/chrome/app/chromeos_strings.grdp
[modify] https://crrev.com/168ecd71dbd357efb815c2b8380a434331d4cae7/chrome/browser/chromeos/events/event_rewriter.cc
[modify] https://crrev.com/168ecd71dbd357efb815c2b8380a434331d4cae7/chrome/browser/chromeos/events/event_rewriter.h
[modify] https://crrev.com/168ecd71dbd357efb815c2b8380a434331d4cae7/chrome/browser/chromeos/events/event_rewriter_unittest.cc
[modify] https://crrev.com/168ecd71dbd357efb815c2b8380a434331d4cae7/chrome/browser/chromeos/preferences.cc
[modify] https://crrev.com/168ecd71dbd357efb815c2b8380a434331d4cae7/chrome/browser/resources/options/chromeos/keyboard_overlay.html
[modify] https://crrev.com/168ecd71dbd357efb815c2b8380a434331d4cae7/chrome/browser/ui/webui/options/chromeos/keyboard_handler.cc
[modify] https://crrev.com/168ecd71dbd357efb815c2b8380a434331d4cae7/chrome/common/pref_names.cc
[modify] https://crrev.com/168ecd71dbd357efb815c2b8380a434331d4cae7/chrome/common/pref_names.h
[modify] https://crrev.com/168ecd71dbd357efb815c2b8380a434331d4cae7/tools/metrics/actions/actions.xml
[modify] https://crrev.com/168ecd71dbd357efb815c2b8380a434331d4cae7/ui/base/ime/chromeos/ime_keyboard.h

remaining issue is to add this to MD Settings.

Making P1 since we need parity with current Settings to ship.

 Issue 642786  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4d77b0e6f0b1ee3fc3b9a1ddb268d86f7c29f065

commit 4d77b0e6f0b1ee3fc3b9a1ddb268d86f7c29f065
Author: michaelpg <michaelpg@chromium.org>
Date: Wed Nov 09 01:46:08 2016

MD Settings: Add remapping options for Backspace and Escape

These keys were added in Options when we added support for remapping to
and from these keys. This completes  crbug.com/608625  by adding the same
options to Settings.

BUG= 608625 
R=stevenjb@chromium.org
TEST=Backspace and Escape can be remapped in chrome://md-settings Keyboard
     settings, and are included in the dropdown of keys to map to.
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2449723002
Cr-Commit-Position: refs/heads/master@{#430815}

[modify] https://crrev.com/4d77b0e6f0b1ee3fc3b9a1ddb268d86f7c29f065/chrome/app/settings_strings.grdp
[modify] https://crrev.com/4d77b0e6f0b1ee3fc3b9a1ddb268d86f7c29f065/chrome/browser/extensions/api/settings_private/prefs_util.cc
[modify] https://crrev.com/4d77b0e6f0b1ee3fc3b9a1ddb268d86f7c29f065/chrome/browser/resources/settings/device_page/compiled_resources2.gyp
[modify] https://crrev.com/4d77b0e6f0b1ee3fc3b9a1ddb268d86f7c29f065/chrome/browser/resources/settings/device_page/keyboard.html
[modify] https://crrev.com/4d77b0e6f0b1ee3fc3b9a1ddb268d86f7c29f065/chrome/browser/resources/settings/device_page/keyboard.js
[modify] https://crrev.com/4d77b0e6f0b1ee3fc3b9a1ddb268d86f7c29f065/chrome/browser/ui/webui/settings/md_settings_localized_strings_provider.cc
[modify] https://crrev.com/4d77b0e6f0b1ee3fc3b9a1ddb268d86f7c29f065/chrome/test/data/webui/settings/device_page_tests.js

Thanks a lot for doing this. I wish I still had my Chromebook to try this out, but I am pretty sure thousands of power users around the world will appreciate the change.

who do you think lobbied for Backspace? :-P

Verified on ChromeOS 9000.0.0, 56.0.2923.0