Merge to XFA: Move zlib to third_party/

(cherry picked from commit 959eb05140a8f5af7724a2da4cf5d04e2e50f4a6)
Original Review URL: https://codereview.chromium.org/1197693003.

TBR=thestig@chromium.org

Review URL: https://codereview.chromium.org/1197863002.
diff --git a/third_party/BUILD.gn b/third_party/BUILD.gn
index c988e7d..549df8a 100644
--- a/third_party/BUILD.gn
+++ b/third_party/BUILD.gn
@@ -225,6 +225,31 @@
   ]
 }
 
+source_set("fx_zlib") {
+  configs -= [ "//build/config/compiler:chromium_code" ]
+  configs += [
+    "//build/config/compiler:no_chromium_code",
+    "//third_party/pdfium:pdfium_config",
+  ]
+  sources = [
+    "zlib_v128/adler32.c",
+    "zlib_v128/compress.c",
+    "zlib_v128/crc32.c",
+    "zlib_v128/deflate.c",
+    "zlib_v128/gzclose.c",
+    "zlib_v128/gzlib.c",
+    "zlib_v128/gzread.c",
+    "zlib_v128/gzwrite.c",
+    "zlib_v128/infback.c",
+    "zlib_v128/inffast.c",
+    "zlib_v128/inflate.c",
+    "zlib_v128/inftrees.c",
+    "zlib_v128/trees.c",
+    "zlib_v128/uncompr.c",
+    "zlib_v128/zutil.c",
+  ]
+}
+
 source_set("pdfium_base") {
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [