Merge "DO NOT MERGE ANYWHERE: ImageReader: Add discardFreeBuffers method" into nyc-dev am: e93c655093  -s ours am: def3c209db  -s ours am: d28f5d5e5a  -s ours
am: 3558072a43  -s ours

Change-Id: I57e35df54044c72775aa7108c3a5bdde45f42440