Set Metal rendertargetproxy via drawableSize

Bug: skia:
Change-Id: Idfe709836a9c0be5ce9b6fd200956ff8e284596d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/249981
Reviewed-by: Hal Canary <halcanary@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>

Author: jvanverth

src/image/SkSurface_GpuMtl.mm

@@ -48,19 +48,19 @@
     }
 
     GrSurfaceDesc desc;
-    desc.fWidth = metalLayer.drawableSize.width * metalLayer.contentsScale;
-    desc.fHeight = metalLayer.drawableSize.height * metalLayer.contentsScale;
+
+    desc.fWidth = metalLayer.drawableSize.width;
+    desc.fHeight = metalLayer.drawableSize.height;
     desc.fConfig = config;
 
     sk_sp<GrRenderTargetProxy> proxy = proxyProvider->createLazyRenderTargetProxy(
             [layer, drawable, sampleCnt, config](GrResourceProvider* resourceProvider) {
                 CAMetalLayer* metalLayer = (__bridge CAMetalLayer*)layer;
                 id<CAMetalDrawable> currentDrawable = [metalLayer nextDrawable];
 
-                CGSize size = [metalLayer drawableSize];
                 GrSurfaceDesc desc;
-                desc.fWidth = size.width;
-                desc.fHeight = size.height;
+                desc.fWidth = metalLayer.drawableSize.width;
+                desc.fHeight = metalLayer.drawableSize.height;
                 desc.fConfig = config;
 
                 GrMtlGpu* mtlGpu = (GrMtlGpu*) resourceProvider->priv().gpu();