Apply diff annotations (intraline differences and comment ranges) by
executing the annotation layers in order to each line. The diff builder
maintains an ordered array of annotation layers which are communicated
to GrDiffBuilder subclass instances. The builder also listens to each
layer for notifications that annotations have changed for some line
range and re-renders (i.e. re-applies the pipeline on DIV.contentText
elements) accordingly.
Change-Id: Iea0599d4869cafaadc0974158153a91d927913e8
d0dd392794