Use const references to keys and values where appropriate to avoid
copying them unnecessarily.
Deleted some dead code.
Simplified a few pieces that were doing unnecessary redundant work.
Change-Id: Ib2145b7094a40db2d679e05dafe050fe1e87b846
- use GenerationCache for caching
- move GenerationCache.h from libs/hwui/utils to include/utils
- add #define for cache activation / deactivation
Change-Id: Ifaf519f0b5e33b087a453e4aa6430162d8438f20