Add GM for crbug:10141204

Bug: skia:9779, chromium:10141204
Change-Id: If075e04373a141343ce368c1b28a494047a396f9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/265876
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>

gm/crbug_1041204.cpp

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2020 Google LLC
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "gm/gm.h"
+#include "include/core/SkCanvas.h"
+#include "include/core/SkColor.h"
+#include "include/core/SkMatrix.h"
+
+DEF_SIMPLE_GM(crbug_10141204, canvas, 512, 512) {
+    // While the coordinates are giant and the transform is not axis-aligned, this should
+    // fill the screen left side with solid blue. This has an extra zoom factor compared to the
+    // canvas JS in order to more visibly highlight the numerical issues that caused the bug.
+    // (The original transform would have completely filled the screen with solid blue, so the bug
+    // manifested as an improper discard on occasion. With the new scale factor, the bug manifests
+    // as either an improper fullscreen clear or an improper discard, instead).
+    SkScalar extraZoom = exp(-2.3f);
+    canvas->scale(extraZoom, extraZoom);
+    canvas->scale(2.f, 2.f);
+    canvas->concat(SkMatrix::MakeAll(
+            -0.0005550860255665798f, -0.0030798374421905717f, -0.014111959825129805f,
+            -0.07569627776417084f, 232.00000000000017f, 39.999999999999936f,
+            0.f, 0.f, 1.f));
+    canvas->translate(-3040103.0493857153f, 337502.1103282161f);
+    canvas->scale(9783.93962050256f, -9783.93962050256f);
+
+    SkPaint paint;
+    paint.setColor(SK_ColorBLUE);
+    paint.setAntiAlias(true);
+    canvas->drawRect(SkRect::MakeWH(512, 512), paint);
+}

gn/gm.gni

@@ -120,6 +120,7 @@ gm_sources = [
   "$_gm/crbug_946965.cpp",
   "$_gm/crbug_947055.cpp",
   "$_gm/crbug_996140.cpp",
+  "$_gm/crbug_1041204.cpp",
   "$_gm/croppedrects.cpp",
   "$_gm/crosscontextimage.cpp",
   "$_gm/cubicpaths.cpp",