Update Shaders tab in Viewer.

- Added "Dump Shaders" button; this writes the shaders to disk in the
  `/resources/sksl` directory. This will allow us to more easily check
  real-world shader code generation, instead of synthetic examples.
- Renamed "Load" and "Save" to "View" and "Apply Changes," to clarify
  that they are not about files on disk. (Otherwise they seemed
  confusing when placed next to a Dump Shaders button.)

Also, fixed a bug which would prevent a new deferred action from being
registered while running deferred actions.

(This CL implements the "test real-world shaders" portion of
http://go/optimization-in-sksl)

Change-Id: I7626a9e9c4f3ecb31b51f29b8106e4ca55de4dd4
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/380317
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
2 files changed