https://codereview.chromium.org/1830973002 fixed this bug. Re-enable the
tests and remove comments referencing it.

BUG=skia:4822
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1830163002

Review URL: https://codereview.chromium.org/1830163002
diff --git a/dm/DM.cpp b/dm/DM.cpp
index 9b3a42f..ce3a1aa 100644
--- a/dm/DM.cpp
+++ b/dm/DM.cpp
@@ -589,10 +589,7 @@
     }
 
     // Push image generator GPU test.
-    // FIXME: The gpu backend does not draw kGray sources correctly. (skbug.com/4822)
-    if (kGray_8_SkColorType != codec->getInfo().colorType()) {
-        push_image_gen_src(path, ImageGenSrc::kCodec_Mode, codec->getInfo().alphaType(), true);
-    }
+    push_image_gen_src(path, ImageGenSrc::kCodec_Mode, codec->getInfo().alphaType(), true);
 
     // Push image generator CPU tests.
     for (SkAlphaType alphaType : alphaModes) {
diff --git a/dm/DMSrcSink.cpp b/dm/DMSrcSink.cpp
index 78782a0..1cffb3c 100644
--- a/dm/DMSrcSink.cpp
+++ b/dm/DMSrcSink.cpp
@@ -831,10 +831,6 @@
 
     // Test deferred decoding path on GPU
     if (fIsGpu) {
-        // FIXME: The gpu backend does not draw kGray sources correctly. (skbug.com/4822)
-        //        We have disabled these tests in DM.cpp.
-        SkASSERT(kGray_8_SkColorType != gen->getInfo().colorType());
-
         sk_sp<SkImage> image(SkImage::MakeFromGenerator(gen.release(), nullptr));
         if (!image) {
             return "Could not create image from codec image generator.";