bug:18667472 Previously, we were allocating per-frame temporary paths within the PlaybackStateStruct, but these are not safe as layers allocate these transiently. Instead, move these to the OpenGLRenderer, which has better define lifecycle. Additionally, don't store SkPath objects directly in vector, since they are then subject to relocation. Change-Id: I8187ef542fcd5b030502bb75eb123ee26c0daa96