Fix ClangTidy `performance-unnecessary-value-param` findings.

This is only a small subset of the findings, but it's a good
starting point. We save a few K of code size from removing
unnecessary copies and ref-count bumps.

Change-Id: Ibe9c02b1d3cc60592cf7eb689acd9b5d549f8ae6
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/766634
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Nicolette Prevost <nicolettep@google.com>
Commit-Queue: Nicolette Prevost <nicolettep@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
50 files changed