Add RAW decoding into Skia.

TBR=reed@google.com

BUG=skia:

(Based on the work from ebrauer in https://codereview.chromium.org/1459473007)
(Based on the work from adaubert in https://codereview.chromium.org/1494003003)
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1520403003

Committed: https://skia.googlesource.com/skia/+/6bd8639f8c142eedf543f4e5f3b02d2bf11df308

Review URL: https://codereview.chromium.org/1520403003
diff --git a/tests/CodexTest.cpp b/tests/CodexTest.cpp
index 2768d57..5210cf4 100644
--- a/tests/CodexTest.cpp
+++ b/tests/CodexTest.cpp
@@ -450,6 +450,9 @@
     check(r, "plane_interlaced.png", SkISize::Make(250, 126), true, false, false);
     check(r, "randPixels.png", SkISize::Make(8, 8), true, false, false);
     check(r, "yellow_rose.png", SkISize::Make(400, 301), true, false, false);
+
+    // RAW
+    check(r, "sample_1mp.dng", SkISize::Make(600, 338), false, false, false);
 }
 
 // Test interlaced PNG in stripes, similar to DM's kStripe_Mode
@@ -643,6 +646,8 @@
     test_dimensions(r, "1x16.png");
     test_dimensions(r, "mandrill_16.png");
 
+    // RAW
+    test_dimensions(r, "sample_1mp.dng");
 }
 
 static void test_invalid(skiatest::Reporter* r, const char path[]) {