(#2890) - reduce md5 chunk size to 32768

[nolanlawson]

This is hardly a slam dunk, but by reducing the md5 chunk size, it seems to me to block DOM rendering much less than before.

In these videos I'm loading some large-ish GIFs wholesale into WebSQL in a WebView on a Nexus 5 running Android 4.4.4. The Blobs are provided via xhr with xhr.responseType = 'arraybuffer', then new Blob().

Before 1, After 1
Before 2, After 2

The DOM is still obviously getting blocked, because the GIFs freeze, but they seem to freeze a bit less when the chunk size is lower. But even if it's just my imagination, can we agree that 32KB is a more reasonable default than 500KB in browsers? Or that maybe we should make this configurable?

[nolanlawson]

I still stand by this commit, although #2900 has a way more visible impact.

[calvinmetcalf]

cb65153