Chris Bracken d43d353475 Use iOS scale when computing render buffer size (#4171)
When checking whether render buffer size has changed, apply the device
scale factor used to convert points to pixels to ensure we're not
needlessly re-allocating render buffer storage.

Adds trace + debug log to make this easier to detect in future.

Originally introduced in 2d530daeca438ca24562d290616c0aec5ab76b88, but
rolled back in 0a6e415b60581ef7934032df20401da1fae9ea9f to test whether
it was responsible for regressions to
flutter_gallery_ios__transition_perf benchmarks:
  * average_frame_build_time_millis
  * missed_frame_build_budget_count
2017-10-03 19:43:36 -07:00
..