Focus SkScaledCodec on BitmapRegionDecoder

tests/CodexTest.cpp

Index: tests/CodexTest.cpp
diff --git a/tests/CodexTest.cpp b/tests/CodexTest.cpp
index f1c5bbaa128e1c989bf06af39f27f7a22e211864..b6ff08cdd7e149e4ad17c6fc83b01693ffeebebe 100644
--- a/tests/CodexTest.cpp
+++ b/tests/CodexTest.cpp
@@ -362,8 +362,11 @@ DEF_TEST(Codec_stripes, r) {
 }
 
 static void test_invalid_stream(skiatest::Reporter* r, const void* stream, size_t len) {
+    // Neither of these calls should return a codec. Bots should catch us if we leaked anything.
     SkCodec* codec = SkCodec::NewFromStream(new SkMemoryStream(stream, len, false));
-    // We should not have gotten a codec. Bots should catch us if we leaked anything.
+    REPORTER_ASSERT(r, !codec);
+
+    codec = SkScaledCodec::NewFromStream(new SkMemoryStream(stream, len, false));
     REPORTER_ASSERT(r, !codec);
 }
 
@@ -390,6 +393,16 @@ DEF_TEST(Codec_leaks, r) {
     test_invalid_stream(r, emptyGif, sizeof(emptyGif));
 }
 
+DEF_TEST(Codec_null, r) {
+    // Attempting to create an SkCodec or an SkScaledCodec with null should not
+    // crash.
+    SkCodec* codec = SkCodec::NewFromStream(nullptr);
+    REPORTER_ASSERT(r, !codec);
+
+    codec = SkScaledCodec::NewFromStream(nullptr);
+    REPORTER_ASSERT(r, !codec);
+}
+
 static void test_dimensions(skiatest::Reporter* r, const char path[]) {
     // Create the codec from the resource file
     SkAutoTDelete<SkStream> stream(resource(path));