Ensure that ChromeEarlGreyUIImpl reports correct line number on failure.

This is done by replacing EarlGrey object with [self earlGrey].
[self earlGrey] is provided by a superclass and returns EarlGreyImpl
object created with correct line number and filename (taken from the
place of ChromeEarlGreyUI macro instantiation).

References to ChromeEarlGreyUI were replaced with self to avoid
recreating ChromeEarlGreyUIImpl object with incorrect line number.

Bug: 963613
Change-Id: Ie1d56a77b080f0ce1efb81ac7240fb3610cebbd9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1617891
Commit-Queue: Eugene But <eugenebut@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Auto-Submit: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#662388}
3 files changed