[FS] Fix dcheck when no accepted file types are provided.

The file_type_index passed to SelectFileDialog::SelectFile can't be 1
(the first accepted type) if no explicitly accepted types are provided.

Bug: 1112122
Change-Id: If72b971be087c3b9b7142b6754f887e70f122fd5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2333036
Commit-Queue: Victor Costan <pwnall@chromium.org>
Auto-Submit: Marijn Kruisselbrink <mek@chromium.org>
Reviewed-by: Victor Costan <pwnall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#794872}

content/browser/native_file_system/file_system_chooser.cc

@@ -133,7 +133,8 @@ FileSystemChooser::Options::Options(
     std::vector<blink::mojom::ChooseFileSystemEntryAcceptsOptionPtr> accepts,
     bool include_accepts_all)
     : type_(type),
-      file_types_(ConvertAcceptsToFileTypeInfo(accepts, include_accepts_all)) {}
+      file_types_(ConvertAcceptsToFileTypeInfo(accepts, include_accepts_all)),
+      default_file_type_index_(file_types_.extensions.empty() ? 0 : 1) {}
 
 // static
 void FileSystemChooser::CreateAndShow(
@@ -178,7 +179,7 @@ void FileSystemChooser::CreateAndShow(
   listener->dialog_->SelectFile(
       dialog_type, /*title=*/base::string16(),
       /*default_path=*/base::FilePath(), &options.file_type_info(),
-      /*file_type_index=*/1,
+      options.default_file_type_index(),
       /*default_extension=*/base::FilePath::StringType(),
       web_contents ? web_contents->GetTopLevelNativeWindow() : nullptr,
       /*params=*/nullptr);

content/browser/native_file_system/file_system_chooser.h

@@ -42,10 +42,12 @@ class CONTENT_EXPORT FileSystemChooser : public ui::SelectFileDialog::Listener {
     const ui::SelectFileDialog::FileTypeInfo& file_type_info() const {
       return file_types_;
     }
+    int default_file_type_index() const { return default_file_type_index_; }
 
    private:
     blink::mojom::ChooseFileSystemEntryType type_;
     ui::SelectFileDialog::FileTypeInfo file_types_;
+    int default_file_type_index_ = 0;
   };
 
   static void CreateAndShow(WebContents* web_contents,