Remove uses of SkImageDecoder from samplecode

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1812323003

Review URL: https://codereview.chromium.org/1812323003
diff --git a/samplecode/SampleLighting.cpp b/samplecode/SampleLighting.cpp
index 566ed7f..fa88e3e 100755
--- a/samplecode/SampleLighting.cpp
+++ b/samplecode/SampleLighting.cpp
@@ -5,11 +5,11 @@
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
+#include "DecodeFile.h"
 #include "SampleCode.h"
 #include "Resources.h"
 
 #include "SkCanvas.h"
-#include "SkImageDecoder.h"
 #include "SkLightingShader.h"
 #include "SkPoint3.h"
 
@@ -39,9 +39,9 @@
 
     LightingView() {
         SkString diffusePath = GetResourcePath("brickwork-texture.jpg");
-        SkImageDecoder::DecodeFile(diffusePath.c_str(), &fDiffuseBitmap);
+        decode_file(diffusePath.c_str(), &fDiffuseBitmap);
         SkString normalPath = GetResourcePath("brickwork_normal-map.jpg");
-        SkImageDecoder::DecodeFile(normalPath.c_str(), &fNormalBitmap);
+        decode_file(normalPath.c_str(), &fNormalBitmap);
 
         fLightAngle = 0.0f;
         fColorFactor = 0.0f;