Rewrite SkTRegistry to take any trivially-copyable type.

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 d368eccd92d629537ae7b8cedf68b1dc29d81970..1df6924c03dde4b0b9b28082c556e4616d35f29c 100644
--- a/src/images/SkImageDecoder_libgif.cpp
+++ b/src/images/SkImageDecoder_libgif.cpp
@@ -377,7 +377,7 @@ static SkImageDecoder* sk_libgif_dfactory(SkStream* stream) {
     return NULL;
 }
 
-static SkTRegistry<SkImageDecoder*, SkStream*> gReg(sk_libgif_dfactory);
+static SkTRegistry<SkImageDecoder*(*)(SkStream*)> gReg(sk_libgif_dfactory);
 
 static SkImageDecoder::Format get_format_gif(SkStream* stream) {
     if (is_gif(stream)) {
@@ -386,4 +386,4 @@ static SkImageDecoder::Format get_format_gif(SkStream* stream) {
     return SkImageDecoder::kUnknown_Format;
 }
 
-static SkTRegistry<SkImageDecoder::Format, SkStream*> gFormatReg(get_format_gif);
+static SkTRegistry<SkImageDecoder::Format(*)(SkStream*)> gFormatReg(get_format_gif);