Revert of Make SkPicture/SkImageGenerator default to SkCodec

bench/ETCBitmapBench.cpp

Index: bench/ETCBitmapBench.cpp
diff --git a/bench/ETCBitmapBench.cpp b/bench/ETCBitmapBench.cpp
index 305f49210850f338880ec859f4aa1ec68eda1204..1b06112996269e4cf52b8bffd7e615e8c9a4f026 100644
--- a/bench/ETCBitmapBench.cpp
+++ b/bench/ETCBitmapBench.cpp
@@ -72,9 +72,6 @@
     }
     return newData;
 }
-
-// Defined in SkImageDecoder_ktx.cpp
-extern SkImageGenerator* decoder_image_generator(SkData*);
 
 // This is the base class for all of the benches in this file. In general
 // the ETC1 benches should all be working on the same data. Due to the
@@ -154,10 +151,10 @@
         }
 
         if (fDecompress) {
-            SkAutoTDelete<SkImageGenerator> gen(decoder_image_generator(fPKMData));
+            SkAutoTDelete<SkImageGenerator> gen(SkImageGenerator::NewFromEncoded(fPKMData));
             gen->generateBitmap(&fBitmap);
         } else {
-            fImage.reset(SkImage::NewFromGenerator(decoder_image_generator(fPKMData)));
+            fImage.reset(SkImage::NewFromEncoded(fPKMData));
         }
     }