Clarify that AppIconLoader::icon_size is in DIP

As is, "icon_size" is an int, and it's not immediately obvious whether
that's measured in DIPs (Density Indepent Pixels) or in physical pixels.

Also change ChromeAppIconLoader's argument name from "etc_dips" to
"etc_dip", consistent with the vast majority of Chromium code:

https://cs.chromium.org/search/?q=in_dip&sq=package:chromium&type=cs

https://cs.chromium.org/search/?q=in_dips&sq=package:chromium&type=cs

Change-Id: I94495ca4f357c52106aab331581d90a0d7e82a6b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1510695
Reviewed-by: Yury Khmel <khmel@chromium.org>
Reviewed-by: Trent Apted <tapted@chromium.org>
Reviewed-by: Ben Wells <benwells@chromium.org>
Commit-Queue: Nigel Tao <nigeltao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#640627}
7 files changed