ARC file picker : Allow the user to select all files when MIME type conversion partially fails

https://screenshot.googleplex.com/Bov9fKoBQ6y.png

BUG=b:133848333
TEST=Open files app with unknown MIME type and check the bottom left dropdown in the file selector

Change-Id: I9c9f40ca623821e95f9e3d50a792413e3220d0d3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1638205
Commit-Queue: Satoshi Niwa <niwa@chromium.org>
Reviewed-by: Ryo Hashimoto <hashimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#665074}

chrome/browser/chromeos/arc/fileapi/arc_select_files_handler.cc

@@ -143,8 +143,12 @@ void BuildFileTypeInfo(const mojom::SelectFilesRequestPtr& request,
   for (const std::string& mime_type : request->mime_types) {
     std::vector<base::FilePath::StringType> extensions;
     net::GetExtensionsForMimeType(mime_type, &extensions);
-    if (!extensions.empty())
+    if (extensions.empty()) {
+      // Allow the user to select all files if MIME type conversion fails.
+      file_type_info->include_all_files = true;
+    } else {
       file_type_info->extensions.push_back(extensions);
+    }
   }
 }