Bitmap.asImage()

... and lots and lots of IWYU

Change-Id: Ie5157dcdd2e6d29b95c71b39153278ab48ef4eb3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/346778
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
diff --git a/tests/GradientTest.cpp b/tests/GradientTest.cpp
index 9595ffa..709e403 100644
--- a/tests/GradientTest.cpp
+++ b/tests/GradientTest.cpp
@@ -5,6 +5,7 @@
  * found in the LICENSE file.
  */
 
+#include "include/core/SkBitmap.h"
 #include "include/core/SkCanvas.h"
 #include "include/core/SkColorPriv.h"
 #include "include/core/SkShader.h"