Remove superfluous ChromeLanguageDetectionTabHelper

This simplifies the IPC setup for translate, in preparation of enabling
it in subframes.

ChromeLanguageDetectionTabHelper's purpose is to establish the binding
between the per-frame TranslateHelper objects and the per-WebContents
ContentTranslateDriver. It is redundant with ContentTranslateDriver, so
this CL removes it and moves its functionality to the driver.

This will make some subsequent changes to this system (to enable
subframe translations) simpler.

Change-Id: I3418f7312339e72b095e5488f9cc7756c326dcd2
Reviewed-on: https://chromium-review.googlesource.com/c/1407768
Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Mathieu Perreault <mathp@chromium.org>
Commit-Queue: anthonyvd <anthonyvd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#623810}
13 files changed