08c8583aea
In BBOTA, we generate patches based on _all_ the blocks of a pair of input files (src and tgt). For security incremental OTAs, one common pattern is that only a few blocks are changed in odex files (e.g. headers). We don't really need to stash/patch the unchanged blocks. This CL analyzes the unchanged blocks in odex files and computes the diff for the changed blocks only. It reduces the OTA install time by about 25% to 40% in our experiments, by paying an increase of 5% to 30% OTA generation time cost. Bug: 31570716 Test: Generate an incremental and apply on device. Change-Id: If842c1afeff6894a3d27eb60b7e8f65a179b7977