Rename Jbig2Module to Jbig2Decoder.

Change-Id: I0c071931ca3eeb175499f4939e60a811f7064e52
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/69915
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/core/fxcodec/BUILD.gn b/core/fxcodec/BUILD.gn
index 99122f1..41270b4 100644
--- a/core/fxcodec/BUILD.gn
+++ b/core/fxcodec/BUILD.gn
@@ -56,8 +56,8 @@
     "jbig2/JBig2_SymbolDict.h",
     "jbig2/JBig2_TrdProc.cpp",
     "jbig2/JBig2_TrdProc.h",
-    "jbig2/jbig2module.cpp",
-    "jbig2/jbig2module.h",
+    "jbig2/jbig2_decoder.cpp",
+    "jbig2/jbig2_decoder.h",
     "jpeg/jpeg_common.cpp",
     "jpeg/jpeg_common.h",
     "jpeg/jpegmodule.cpp",