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Provide some basic info of the host of the focused text field to system
IME via private extension API. With these information, IME will identify
some known faulty clients then demote its input.ime APIs (even disable
advanced features) to make the typing on these client works basically.

Context for the CL:
Due to some faulty implementation of their text operations in some
clients' text field (e.g. Terminal for Linux, Text app, Android app...)
in ChromeOS, they don't work not properly with predefined ChromeOS IME
APIs (e.g. chrome.input.ime.deleteSurroundingText, setComposingRange...).

Therefore, typing on these client are always difficult with unexpected
results. Detailed example can be found in the bugs attached.

Tested=Some popular cases in local VM and Kevin device in skylib.

Bug: b/162183648,b/163645900
Change-Id: Ib43e9ccba7e9620b7189153d956ef685f80fb29d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2405046
Commit-Queue: Leo Zhang <googleo@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Reviewed-by: Yuichiro Hanada <yhanada@chromium.org>
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#807764}