Web MIDI: use GetVendorName() result only if it is available

media/midi/midi_manager_win.cc

Index: media/midi/midi_manager_win.cc
diff --git a/media/midi/midi_manager_win.cc b/media/midi/midi_manager_win.cc
index 926fe291483348d45310b2b285b90c9c2b8198ab..1d140c3d7a40a2b42884580a80ec64e04c5b77c4 100644
--- a/media/midi/midi_manager_win.cc
+++ b/media/midi/midi_manager_win.cc
@@ -291,8 +291,10 @@ struct MidiDeviceInfo final {
 };
 
 std::string GetManufacturerName(const MidiDeviceInfo& info) {
-  if (info.is_usb_device)
-    return device::UsbIds::GetVendorName(info.usb_vendor_id);
+  if (info.is_usb_device) {
+    const char* name = device::UsbIds::GetVendorName(info.usb_vendor_id);
+    return std::string(name ? name : "");
+  }
 
   switch (info.manufacturer_id) {
     case MM_MICROSOFT: