Remove image decoder and encoder autoregistration

src/images/SkImageDecoder_libgif.cpp

Index: src/images/SkImageDecoder_libgif.cpp
diff --git a/src/images/SkImageDecoder_libgif.cpp b/src/images/SkImageDecoder_libgif.cpp
index fb5d18fc0870b1be25caf18aaea110aa5867186a..4c0e181331a1a16d945664ab4ae09ba716b11ffc 100644
--- a/src/images/SkImageDecoder_libgif.cpp
+++ b/src/images/SkImageDecoder_libgif.cpp
@@ -5,10 +5,10 @@
  * found in the LICENSE file.
  */
 
+#include "SkImageDecoder_libgif.h"
 #include "SkColor.h"
 #include "SkColorPriv.h"
 #include "SkColorTable.h"
-#include "SkImageDecoder.h"
 #include "SkRTConf.h"
 #include "SkScaledBitmapSampler.h"
 #include "SkStream.h"
@@ -502,36 +502,19 @@ SkImageDecoder::Result SkGIFImageDecoder::onDecode(SkStream* sk_stream, SkBitmap
     return kSuccess;
 }
 
-///////////////////////////////////////////////////////////////////////////////
-DEFINE_DECODER_CREATOR(GIFImageDecoder);
-///////////////////////////////////////////////////////////////////////////////
-
-static bool is_gif(SkStreamRewindable* stream) {
+SkImageDecoder::Format SkDetectFormatGIFImageDecoder(SkStreamRewindable* stream) {
     char buf[GIF_STAMP_LEN];
     if (stream->read(buf, GIF_STAMP_LEN) == GIF_STAMP_LEN) {
         if (memcmp(GIF_STAMP,   buf, GIF_STAMP_LEN) == 0 ||
                 memcmp(GIF87_STAMP, buf, GIF_STAMP_LEN) == 0 ||
                 memcmp(GIF89_STAMP, buf, GIF_STAMP_LEN) == 0) {
-            return true;
+            return SkImageDecoder::kGIF_Format;
         }
     }
-    return false;
-}
-
-static SkImageDecoder* sk_libgif_dfactory(SkStreamRewindable* stream) {
-    if (is_gif(stream)) {
-        return SkNEW(SkGIFImageDecoder);
-    }
-    return NULL;
-}
-
-static SkImageDecoder_DecodeReg gReg(sk_libgif_dfactory);
-
-static SkImageDecoder::Format get_format_gif(SkStreamRewindable* stream) {
-    if (is_gif(stream)) {
-        return SkImageDecoder::kGIF_Format;
-    }
     return SkImageDecoder::kUnknown_Format;
 }
 
-static SkImageDecoder_FormatReg gFormatReg(get_format_gif);
+SkImageDecoder* SkCreateGIFImageDecoder(SkImageDecoder::Format format) {
+    SkASSERT(SkImageDecoder::kGIF_Format == format);
+    return SkNEW(SkGIFImageDecoder);
+}