More SkISizification in GPU code.

Uses SkISize instead of separate width/height variables in many places.

No functional change.

Change-Id: If87b2c57e43d810f0820c4e3c9ef8e6b8ebd10ba
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/249886
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
diff --git a/src/gpu/GrContext.cpp b/src/gpu/GrContext.cpp
index d9f37f0..f099361 100644
--- a/src/gpu/GrContext.cpp
+++ b/src/gpu/GrContext.cpp
@@ -256,7 +256,7 @@
 
     const GrCaps& caps = *gpuImage->context()->priv().caps();
     int colorSamplesPerPixel = 1;
-    return GrSurface::ComputeSize(caps, proxy->backendFormat(), image->width(), image->height(),
+    return GrSurface::ComputeSize(caps, proxy->backendFormat(), image->dimensions(),
                                   colorSamplesPerPixel, mipMapped, useNextPow2);
 }