It's been driving me nuts that I can't just write `SkMatrix44 m;`,
and I often don't care whether it's initialized or not. The default
identity constructor would be nice to use, but it's deprecated.
By tagging this constructor deprecated, we're only hurting ourselves;
our big clients disable warnings about deprecated routines and use it
freely.
A quick tally in Skia shows we mostly use the uninitialized constructor,
but sometimes the identity constructor, and there is a spread of all
three in Chromium. So I've left the two explicit calls available.
I switched a bunch of calls in Skia to use the less verbose constructor
where it was clear that it didn't matter if the matrix was initialized.
Literally zero of the kUninitialized constructor calls looked important
for performance, so the only place I've kept is its lone unit test.
A few places read clearer with an explicit "identity" to read.
Change-Id: I0573cb6201f5a36f3b43070fb111f7d9af92736f
Reviewed-on: https://skia-review.googlesource.com/c/159480
Reviewed-by: Brian Osman <brianosman@google.com>
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