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This comprises:
  - Attaching an iOS language detection client (similar to the
    existing Content-based client) to each web state
  - Updating the language detection controller (which does the actual
    CLD) to notify the language detection client rather than translate
    code, and to use core datatypes (rather than iOS-specific ones)
  - Updating the translate driver to receive language info via a
    callback from the language detection client
  - Updating unit and integration tests to account for these changes

Bug: 755856
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I7544863835d0d507a3e1453973f55c7fc918ba83
Reviewed-on: https://chromium-review.googlesource.com/740421
Commit-Queue: Michael Martis <martis@chromium.org>
Reviewed-by: Renjie Liu <renjieliu@chromium.org>
Reviewed-by: David Roger <droger@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#513070}