Stop using pendingIO in read/writeSurfacePixels
Stop using pendingIO in read/writeSurfacePixels

This changes the implementation to always flush for these operations.
Once partial DAG flushes are implemented this behavior will be better than the old method.

Change-Id: I1f9edd33dcf5aa15cc5dcdf8f0e06a3b3cd88f48
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/205584
Reviewed-by: Brian Salomon <61fabaaf0876044aeedfd8e351e485c028d69e7b@google.com>
Commit-Queue: Robert Phillips <95e8ac5504948c7bf91b22c16a8dbb7ae7c66bfd@google.com>

rubenvb/skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,google/skia,aosp-mirror/platform_external_skia,rubenvb/skia,HalCanary/skia-hc,google/skia,google/skia,google/skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,google/skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,google/skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,rubenvb/skia,rubenvb/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,google/skia,rubenvb/skia,google/skia,HalCanary/skia-hc,HalCanary/skia-hc,rubenvb/skia,google/skia,rubenvb/skia,HalCanary/skia-hc,rubenvb/skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,rubenvb/skia,rubenvb/skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia