[svg] Adjust container size on Viewer window resize

It's nice to be able to resize the SVG container on the fly.

Change-Id: I6624e6151aaff7e2a7f6eb07e84aee88c4a2e408
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/282418
Auto-Submit: Florin Malita <fmalita@chromium.org>
Commit-Queue: Tyler Denniston <tdenniston@google.com>
Reviewed-by: Tyler Denniston <tdenniston@google.com>
2 files changed