devtools

5fd78a12 - Reduce memory used when saving Performance data for offline viewing (#10034)

Reduce memory used when saving Performance data for offline viewing (#10034) * Reduce memory used when saving Performance data for offline viewing The Perfetto trace was exported as a JSON array of numbers, which makes jsonEncode do roughly two string writes per trace byte and can exhaust the browser's memory for large traces. Export it as a base64 string under a new key instead, and keep reading the legacy list format so older files still load. Also: - Only encode the bytes in a ByteData view when converting to base64. - Allocate Uint8ListRingBuffer.merged once at its exact size. - Show an error instead of crashing when the data is too large to export. - Revoke the download Blob URL after the download starts. Fixes #10010 * Link the PR in the release note * Address review feedback on performance export --------- Co-authored-by: Sam Rawlins <srawlins@google.com>