Remove image decoder and encoder autoregistration

src/images/SkImageDecoder_pkm.cpp

Index: src/images/SkImageDecoder_pkm.cpp
diff --git a/src/images/SkImageDecoder_pkm.cpp b/src/images/SkImageDecoder_pkm.cpp
index 746ae40c4c287a44839ad6d22d4fa84acd402742..347f162a4d8aa5e836c9a6b93bc3c7cb28fe7e13 100644
--- a/src/images/SkImageDecoder_pkm.cpp
+++ b/src/images/SkImageDecoder_pkm.cpp
@@ -4,9 +4,8 @@
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
-
+#include "SkImageDecoder_pkm.h"
 #include "SkColorPriv.h"
-#include "SkImageDecoder.h"
 #include "SkScaledBitmapSampler.h"
 #include "SkStream.h"
 #include "SkStreamPriv.h"
@@ -102,34 +101,17 @@ SkImageDecoder::Result SkPKMImageDecoder::onDecode(SkStream* stream, SkBitmap* b
     return kSuccess;
 }
 
-/////////////////////////////////////////////////////////////////////////////////////////
-DEFINE_DECODER_CREATOR(PKMImageDecoder);
-/////////////////////////////////////////////////////////////////////////////////////////
-
-static bool is_pkm(SkStreamRewindable* stream) {
-    // Read the PKM header and make sure it's valid.
+SkImageDecoder::Format SkDetectFormatPKMImageDecoder(SkStreamRewindable* stream) {
     unsigned char buf[ETC_PKM_HEADER_SIZE];
-    if (stream->read((void*)buf, ETC_PKM_HEADER_SIZE) != ETC_PKM_HEADER_SIZE) {
-        return false;
-    }
-
-    return SkToBool(etc1_pkm_is_valid(buf));
-}
-
-static SkImageDecoder* sk_libpkm_dfactory(SkStreamRewindable* stream) {
-    if (is_pkm(stream)) {
-        return SkNEW(SkPKMImageDecoder);
+    if (stream->read((void*)buf, ETC_PKM_HEADER_SIZE) != ETC_PKM_HEADER_SIZE ||
+            !etc1_pkm_is_valid(buf)) {
+        return SkImageDecoder::kUnknown_Format;
     }
-    return NULL;
+    return SkImageDecoder::kPKM_Format;
 }
 
-static SkImageDecoder_DecodeReg gReg(sk_libpkm_dfactory);
-
-static SkImageDecoder::Format get_format_pkm(SkStreamRewindable* stream) {
-    if (is_pkm(stream)) {
-        return SkImageDecoder::kPKM_Format;
-    }
-    return SkImageDecoder::kUnknown_Format;
+SkImageDecoder* SkCreatePKMImageDecoder(SkImageDecoder::Format format) {
+    SkASSERT(SkImageDecoder::kPKM_Format == format);
+    return SkNEW(SkPKMImageDecoder);
 }
 
-static SkImageDecoder_FormatReg gFormatReg(get_format_pkm);