Revert "Listen to UsbDeviceManager instead of UsbService in UsbChooserContext."

This reverts commit a0f301ad19908c1320f0b00d87f0469b6009b5a6.

Reason for revert: Suspect that is causes test failures in Linux ASan, see https://crbug.com/883262.

Original change's description:
> Listen to UsbDeviceManager instead of UsbService in UsbChooserContext.
> 
> For UsbService::Observer, "OnDeviceRemovedCleanup" needs to be handled
> after "OnDeviceRemoved". But for mojom interface UsbDeviceManager,
> there is no way to provide such dependency among listeners.
> 
> As all users will be converted from UsbService to UsbDeviceManager,
> to avoid the potential race condition, WebUsbServiceImpl is made
> listen to UsbChooserContext in this CL.
> 
> Bug: 699790
> Change-Id: I1e3b45196552e987b7422b127651e1fb01e1618b
> Reviewed-on: https://chromium-review.googlesource.com/1210386
> Commit-Queue: Donna Wu <donna.wu@intel.com>
> Reviewed-by: Reilly Grant <reillyg@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#590609}

TBR=reillyg@chromium.org,donna.wu@intel.com

Change-Id: I954dd50c4cf8b5b761ede371f8ff904c07a61993
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 699790, 883262
Reviewed-on: https://chromium-review.googlesource.com/1222107
Reviewed-by: Adithya Srinivasan <adithyas@chromium.org>
Commit-Queue: Adithya Srinivasan <adithyas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#590720}
11 files changed