//gm/gm.h: Fold GM::onISize() into GM::getISize().

Inspired by https://skia-review.googlesource.com/c/skia/+/742738, this CL aims to simplify GMs by removing the GM::getISize() -> GM::onISize() indirection, which at the moment isn't providing any value.

Unlike the aforementioned CL, I'm leaving GM::getISize() as non-const because some GMs perform non-const initialization steps.

Most changes in the CL are the result of a multifile search/replace and clang-format.

Suggested review order:
- //gm/gm.h
- //gm/gm.cpp
- Everything else.

Bug: b/40045301
Change-Id: Ib51e1034209fda55cd3e1d2cf9617a4b19f27207
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/742740
Auto-Submit: Leandro Lovisolo <lovisolo@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Leandro Lovisolo <lovisolo@google.com>
270 files changed