remove off64_t in SkHeifCodec

I argue int64_t is just as good, and much more familiar.

This, I think, will also fix the Emscripten/wasm bot,
where somewhat bizarrely off64_t is typedef'd to int.

Change-Id: I4eb9d05cbd3066b107fa429beff79e7471e94526
Reviewed-on: https://skia-review.googlesource.com/62362
Reviewed-by: Leon Scroggins <scroggo@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
diff --git a/src/codec/SkHeifCodec.cpp b/src/codec/SkHeifCodec.cpp
index 21828b5..5fef511 100644
--- a/src/codec/SkHeifCodec.cpp
+++ b/src/codec/SkHeifCodec.cpp
@@ -34,7 +34,7 @@
         return false;
     }
 
-    off64_t offset = 8;
+    int64_t offset = 8;
     if (chunkSize == 1) {
         // This indicates that the next 8 bytes represent the chunk size,
         // and chunk data comes after that.
@@ -56,7 +56,7 @@
     if (chunkSize > bytesRead) {
         chunkSize = bytesRead;
     }
-    off64_t chunkDataSize = chunkSize - offset;
+    int64_t chunkDataSize = chunkSize - offset;
     // It should at least have major brand (4-byte) and minor version (4-bytes).
     // The rest of the chunk (if any) is a list of (4-byte) compatible brands.
     if (chunkDataSize < 8) {
diff --git a/src/codec/SkStubHeifDecoderAPI.h b/src/codec/SkStubHeifDecoderAPI.h
index 6987f76..87bfbae 100644
--- a/src/codec/SkStubHeifDecoderAPI.h
+++ b/src/codec/SkStubHeifDecoderAPI.h
@@ -14,7 +14,6 @@
 #include <memory>
 #include <stddef.h>
 #include <stdint.h>
-using off64_t = int64_t;
 
 enum HeifColorFormat {
     kHeifColorFormat_RGB565,