Revert of Disable WebUSB client impl (patchset #2 id:20001 of https://codereview.chromium.org/1308273006/ )
Revert of Disable WebUSB client impl (patchset #2 id:20001 of https://codereview.chromium.org/1308273006/ )

Reason for revert:
Reverting this change as it's safe to enable the WebUSB client impl now. The underlying source of process leaks has been addressed.

BUG=524248,526808,526810

Original issue's description:
> Disable WebUSB client impl
>
> Seeing if this resolves some blink test flake which
> appeared recently.
>
> BUG=524248
> TBR=jam@chromium.org,reillyg@chromium.org
> R=tandrii@chromium.org
>
> Committed: https://crrev.com/d29d4ae3f292c3fc3b423157f6c50f5f128a2326
> Cr-Commit-Position: refs/heads/master@{#345415}

TBR=jam@chromium.org,reillyg@chromium.org,tandrii@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=524248

Review URL: https://codereview.chromium.org/1329583003

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#346715}

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