Add workaround 'fDisallowDirectRG8ReadPixels' for Radeon Pro 5000 GPUs.

The Radeon Pro 5000 series appears to be affected by the same RG8 bug as
the Radeon R9 M300 and Radeon Pro Vega GPUs. This workaround resolves a
DM failure in TransferPixelsTest.

Bug: skia:10256
Change-Id: Ic80aecdba7e2973ddcec78b1c8b665be219249e9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/291048
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
diff --git a/src/gpu/gl/GrGLCaps.cpp b/src/gpu/gl/GrGLCaps.cpp
index 4d6e836..79ffe09 100644
--- a/src/gpu/gl/GrGLCaps.cpp
+++ b/src/gpu/gl/GrGLCaps.cpp
@@ -3942,8 +3942,10 @@
 #ifdef SK_BUILD_FOR_MAC
     // On a MacBookPro 11.5 running MacOS 10.13 with a Radeon M370X the TransferPixelsFrom test
     // fails when transferring out from a GL_RG8 texture using GL_RG/GL_UNSIGNED_BYTE.
+    // The same error also occurs in MacOS 10.15 with a Radeon Pro 5300M.
     formatWorkarounds->fDisallowDirectRG8ReadPixels =
             ctxInfo.renderer() == kAMDRadeonR9M3xx_GrGLRenderer ||
+            ctxInfo.renderer() == kAMDRadeonPro5xxx_GrGLRenderer ||
             ctxInfo.renderer() == kAMDRadeonProVegaxx_GrGLRenderer;
 #endif