Assign "application/vnd.android.package-archive" type to APK files on ChromeOS.

net/base/mime_extension_chromeos.cc

Index: net/base/mime_extension_chromeos.cc
diff --git a/net/base/mime_extension_chromeos.cc b/net/base/mime_extension_chromeos.cc
index 03e8e2594cd424d299aeb5bc960b58b30f53a004..9bc893d24a97c6f315f5ea90e1c8bbc00c96a6cf 100644
--- a/net/base/mime_extension_chromeos.cc
+++ b/net/base/mime_extension_chromeos.cc
@@ -14,6 +14,7 @@ namespace {
 
 static const net::MimeInfo mimetype_extension_mapping[] = {
     {"application/epub+zip", "epub"},
+    {"application/vnd.android.package-archive", "apk"},
     {"application/zip", "zip"},
     {"text/calendar", "ics"},
 };