Retract the SDC from GMs where possible (take 2)

In the future, the SDC won't be return by SkCanvas/SkDevices and gms/tests that rely on it won't be run. These GMs don't actually require the SDC.

There is also some opportunistic renaming going on.
TBR=michaelludwig@google.com

Change-Id: I15cbaf69269892fbbf229c0263b567425049c3f0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/415167
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/gm/rectangletexture.cpp b/gm/rectangletexture.cpp
index e48792d..52aa895 100644
--- a/gm/rectangletexture.cpp
+++ b/gm/rectangletexture.cpp
@@ -43,7 +43,7 @@
 class GrSurfaceDrawContext;
 
 namespace skiagm {
-class RectangleTexture : public GpuGM {
+class RectangleTexture : public GM {
 public:
     RectangleTexture() {
         this->setBGColor(0xFFFFFFFF);
@@ -147,8 +147,7 @@
         fSmallImg = nullptr;
     }
 
-    DrawResult onDraw(GrRecordingContext*, GrSurfaceDrawContext*, SkCanvas* canvas,
-                      SkString*) override {
+    DrawResult onDraw(SkCanvas* canvas, SkString* errorMsg) override {
         SkASSERT(fGradImgs[0] && fGradImgs[1] && fSmallImg);
 
         static constexpr SkScalar kPad = 5.f;