Remove uses of SkImageDecoder from gms

gm/avoidxfermode.cpp

Index: gm/avoidxfermode.cpp
diff --git a/gm/avoidxfermode.cpp b/gm/avoidxfermode.cpp
index a015b6bbe7085e8c01fcf3719ce06523dfe29bb2..acc12577e608c72219eb298490c7cb4239d28410 100644
--- a/gm/avoidxfermode.cpp
+++ b/gm/avoidxfermode.cpp
@@ -8,8 +8,9 @@
 #include "gm.h"
 #include "Resources.h"
 
-#include "SkImageDecoder.h"
 #include "SkAvoidXfermode.h"
+#include "SkData.h"
+#include "SkImage.h"
 #include "SkStream.h"
 
 class AvoidXfermodeGM : public skiagm::GM {
@@ -24,17 +25,10 @@ protected:
     SkISize onISize() override { return SkISize::Make(128, 128); }
 
     void onOnceBeforeDraw() override {
-        SkImageDecoder* codec = nullptr;
-        SkString resourcePath = GetResourcePath("color_wheel.png");
-        SkFILEStream stream(resourcePath.c_str());
-        if (stream.isValid()) {
-            codec = SkImageDecoder::Factory(&stream);
-        }
-        if (codec) {
-            stream.rewind();
-            codec->decode(&stream, &fBM, kN32_SkColorType, SkImageDecoder::kDecodePixels_Mode);
-            delete codec;
-        } else {
+        SkAutoTUnref<SkData> data(SkData::NewFromFileName(
+                GetResourcePath("color_wheel.png").c_str()));
+        SkAutoTDelete<SkImage> image(SkImage::NewFromEncoded(data));
+        if (!image || !image->asLegacyBitmap(&fBM, SkImage::kRW_LegacyBitmapMode)) {
             fBM.allocN32Pixels(1, 1);
             fBM.eraseARGB(255, 255, 0 , 0); // red == bad
         }