Revert "crash_keys: Convert "switches-N", "channel", and client ID to the new API."

This reverts commit 7776d543f6dc862198f22d6e79b9616ea851a603.

Reason for revert:
Looks like this is breaking following tests on the Linux Tests (dbg) bot:

- CrashKeysTest.Switches
- CrashKeysTest.FilterFlags
- CrashKeysTest.VariationsCapacity

See https://uberchromegw.corp.google.com/i/chromium.linux/builders/Linux%20Tests%20%28dbg%29%281%29%2832%29/builds/46786

Original change's description:
> crash_keys: Convert "switches-N", "channel", and client ID to the new API.
> 
> Bug: 598854
> Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
> Change-Id: Ibb9031d4597d4c09bb6105f26aa02103f34b46a8
> Reviewed-on: https://chromium-review.googlesource.com/822833
> Reviewed-by: Mark Mentovai <[email protected]>
> Reviewed-by: Lei Zhang <[email protected]>
> Reviewed-by: Peter Lee <[email protected]>
> Commit-Queue: Robert Sesek <[email protected]>
> Cr-Commit-Position: refs/heads/master@{#524771}

[email protected],[email protected],[email protected],[email protected],[email protected]

Change-Id: Id0c1151b78514e083e36f88e2fd1bd87e364de63
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 598854
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Reviewed-on: https://chromium-review.googlesource.com/833467
Reviewed-by: Hiroki Nakagawa <[email protected]>
Commit-Queue: Hiroki Nakagawa <[email protected]>
Cr-Commit-Position: refs/heads/master@{#524866}