Runtime Effects: Support 'uniform shader' (vs. 'in shader')

The previous behavior leaked Skia-internal concepts into public SkSL.
Users coming from GLSL will expect that bindable/sampleable objects are
uniform (just like texture2D). This keeps the old support around (and
tested), but updates all of our examples to use 'uniform'.

Bug: skia:10679
Change-Id: I0c98162f5e21dad7014d9778ceb26143d2f6030e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/332376
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
diff --git a/samplecode/Sample3D.cpp b/samplecode/Sample3D.cpp
index 9d591a8..1c55a3f 100644
--- a/samplecode/Sample3D.cpp
+++ b/samplecode/Sample3D.cpp
@@ -368,8 +368,8 @@
         fBmpShader = img->makeShader(SkMatrix::Scale(2, 2));
 
         const char code[] = R"(
-            in shader color_map;
-            in shader normal_map;
+            uniform shader color_map;
+            uniform shader normal_map;
 
             layout (marker=local_to_world)          uniform float4x4 localToWorld;
             layout (marker=normals(local_to_world)) uniform float4x4 localToWorldAdjInv;