[Win][MiniBrowser] Download a file, if a MIME type is not supported.

https://bugs.webkit.org/show_bug.cgi?id=259518

Reviewed by Fujii Hironori.

If you select content with an unsupported MIME type, the binary data of
that file will be displayed. Therefore, for such content, download the
file.

* Tools/MiniBrowser/win/WebKitBrowserWindow.cpp:
(WebKitBrowserWindow::decidePolicyForNavigationResponse):

Canonical link: https://commits.webkit.org/266320@main

Tools/MiniBrowser/win/WebKitBrowserWindow.cpp

@@ -510,7 +510,21 @@ void WebKitBrowserWindow::decidePolicyForNavigationResponse(WKPageRef page, WKNa
         text << L"URL: " << createString(adoptWK(WKURLResponseCopyURL(response.get())).get());
         MessageBox(thisWindow.m_hMainWnd, text.str().c_str(), L"No Content", MB_OK | MB_ICONWARNING);
     }
-    WKFramePolicyListenerUse(listener);
+
+    if (WKNavigationResponseCanShowMIMEType(navigationResponse))
+        WKFramePolicyListenerUse(listener);
+    else {
+        std::wstringstream text;
+        text << L"Do you want to save this file?" << std::endl;
+        text << std::endl;
+        text << L"MIME type: " << createString(adoptWK(WKURLResponseCopyMIMEType(response.get())).get()) << std::endl;
+        text << L"URL: " << createString(adoptWK(WKURLResponseCopyURL(response.get())).get());
+
+        if (MessageBox(thisWindow.hwnd(), text.str().c_str(), L"Unsupported MIME type", MB_OKCANCEL | MB_ICONWARNING) == IDOK)
+            WKFramePolicyListenerDownload(listener);
+        else
+            WKFramePolicyListenerIgnore(listener);
+    }
 }
 
 void WebKitBrowserWindow::didFailProvisionalNavigation(WKPageRef page, WKNavigationRef navigation, WKErrorRef error, WKTypeRef userData, const void* clientInfo)