I was wondering if WebGL is considered stable enough to be enabled by default. It makes some PDFs render much faster and it has been off by default for a while now, so we have had quite some time to test it.

If we decide to enable WebGL by default, we should not forget to update https://github.com/mozilla/pdf.js/blob/master/extensions/chromium/preferences_schema.json#L39 as well.

/cc @yurydelendik 
/cc @Snuffleupagus (because IIRC you were testing WebGL too)

if (typeof ImageData !== "undefined" && imgData instanceof ImageData) {
      ctx.putImageData(imgData, 0, 0);
      return;
    }
    
    
    
    
    
    
    
    
    
    
    const height = imgData.height,
      width = imgData.width;
    const partialChunkHeight = height % FULL_CHUNK_HEIGHT;
    const fullChunks = (height - partialChunkHeight) / FULL_CHUNK_HEIGHT;
    const totalChunks = partialChunkHeight === 0 ? fullChunks : fullChunks + 1;
    const chunkImgData = ctx.createImageData(width, FULL_CHUNK_HEIGHT);
    let srcPos = 0,
      destPos;
    const src = imgData.data;
    const dest = chunkImgData.data;
    let i, j, thisChunkHeight, elemsInThisChunk;
    let transferMapRed, transferMapGreen, transferMapBlue, transferMapGray;
    if (transferMaps) {