Revert of Add SkPngChunkReader.

include/core/SkImageDecoder.h

Index: include/core/SkImageDecoder.h
diff --git a/include/core/SkImageDecoder.h b/include/core/SkImageDecoder.h
index 30323b59ee56df2cf7f9ad3ac79d7f5833cbd3ea..144878c1668e74c46922df17ea988f4176e0afb3 100644
--- a/include/core/SkImageDecoder.h
+++ b/include/core/SkImageDecoder.h
@@ -10,13 +10,10 @@
 
 #include "SkBitmap.h"
 #include "SkImage.h"
-#include "SkPngChunkReader.h"
 #include "SkRect.h"
 #include "SkRefCnt.h"
 #include "SkTRegistry.h"
 #include "SkTypes.h"
-
-//#define SK_LEGACY_PEEKER
 
 class SkStream;
 class SkStreamRewindable;
@@ -129,20 +126,23 @@
     */
     bool getRequireUnpremultipliedColors() const { return fRequireUnpremultipliedColors; }
 
-#ifdef SK_LEGACY_PEEKER
-    // Android subclasses SkImageDecoder::Peeker, which has been changed into SkPngChunkReader.
-    // Temporarily use this class until Android can be updated to directly inherit from
-    // SkPngChunkReader.
-    class Peeker : public SkPngChunkReader {
+    /** \class Peeker
+
+        Base class for optional callbacks to retrieve meta/chunk data out of
+        an image as it is being decoded.
+    */
+    class Peeker : public SkRefCnt {
     public:
-        bool readChunk(const char tag[], const void* data, size_t length) final {
-            return this->peek(tag, data, length);
-        }
+        /** Return true to continue decoding, or false to indicate an error, which
+            will cause the decoder to not return the image.
+        */
         virtual bool peek(const char tag[], const void* data, size_t length) = 0;
+    private:
+        typedef SkRefCnt INHERITED;
     };
-#endif
-    SkPngChunkReader* getPeeker() const { return fPeeker; }
-    SkPngChunkReader* setPeeker(SkPngChunkReader*);
+
+    Peeker* getPeeker() const { return fPeeker; }
+    Peeker* setPeeker(Peeker*);
 
     /**
      *  By default, the codec will try to comply with the "pref" colortype
@@ -229,8 +229,8 @@
         to allocate the memory from a cache, volatile memory, or even from
         an existing bitmap's memory.
 
-        If an SkPngChunkReader is installed via setPeeker, it may be used to
-        peek into meta data during the decode.
+        If a Peeker is installed via setPeeker, it may be used to peek into
+        meta data during the decode.
     */
     Result decode(SkStream*, SkBitmap* bitmap, SkColorType pref, Mode);
     Result decode(SkStream* stream, SkBitmap* bitmap, Mode mode) {
@@ -350,7 +350,7 @@
     SkColorType getPrefColorType(SrcDepth, bool hasAlpha) const;
 
 private:
-    SkPngChunkReader*       fPeeker;
+    Peeker*                 fPeeker;
     SkBitmap::Allocator*    fAllocator;
     int                     fSampleSize;
     SkColorType             fDefaultPref;   // use if fUsePrefTable is false