Refactor GetBestPredictorForTile for future tuning.
Refactor GetBestPredictorForTile for future tuning.

This change doesn't impact compression gain or compression speed.

Change-Id: Ia87d8a46c6f1ce0f8974178d75a6b0ba0a6e3696

Aexyn/libwebp,appunite/libwebp,redengineer/libwebp,imazen/libwebp,appunite/libwebp,jacklicn/libwebp,Aexyn/libwebp,kalli123/webm.libwebp,Aexyn/libwebp,ericmckean/webm.libwebp,redengineer/libwebp,Acidburn0zzz/webm.libwebp,comoyo/gonzo-libwebp,kim42083/webm.libwebp,reimaginemedia/webm.libwebp,Acidburn0zzz/webm.libwebp,matanbs/webm.libwebp,yohunl/libwebp,kleopatra999/webm.libwebp,abwiz0086/webm.libwebp,ya7lelkom/libwebp,PKRoma/libwebp,comoyo/gonzo-libwebp,jacklicn/libwebp,imazen/libwebp,zofuthan/libwebp,yohunl/libwebp,keane83/BLE_IM,matanbs/webm.libwebp,abwiz0086/webm.libwebp,ttyangf/libwebp,matanbs/webm.libwebp,kim42083/webm.libwebp,matanbs/webm.libwebp,PKRoma/libwebp,ttyangf/libwebp,PKRoma/libwebp,iniwf/webm.libwebp,Maria1099/webm.libwebp,redengineer/libwebp,kim42083/webm.libwebp,Maria1099/webm.libwebp,PKRoma/libwebp,kim42083/webm.libwebp,iniwf/webm.libwebp,jiehu5114/libwebp,reimaginemedia/webm.libwebp,jiehu5114/libwebp,jiehu5114/libwebp,ttyangf/libwebp,jiehu5114/libwebp,rxl194/libwebp,rxl194/libwebp,webmproject/libwebp,altogother/webm.libwebp,altogother/webm.libwebp,appunite/libwebp,comoyo/gonzo-libwebp,Suvarna1488/webm.libwebp,ya7lelkom/libwebp,kleopatra999/webm.libwebp,kleopatra999/webm.libwebp,PKRoma/libwebp,Acidburn0zzz/webm.libwebp,gshORTON/webm.libwebp,kalli123/webm.libwebp,abwiz0086/webm.libwebp,keane83/BLE_IM,altogother/webm.libwebp,rxl194/libwebp,kalli123/webm.libwebp,gshORTON/webm.libwebp,webmproject/libwebp,gshORTON/webm.libwebp,gshORTON/webm.libwebp,rxl194/libwebp,keane83/BLE_IM,ya7lelkom/libwebp,comoyo/gonzo-libwebp,Suvarna1488/webm.libwebp,matanbs/webm.libwebp,reimaginemedia/webm.libwebp,reimaginemedia/webm.libwebp,zofuthan/libwebp,kalli123/webm.libwebp,yohunl/libwebp,Suvarna1488/webm.libwebp,zofuthan/libwebp,ericmckean/webm.libwebp,ericmckean/webm.libwebp,appunite/libwebp,iniwf/webm.libwebp,ericmckean/webm.libwebp,webmproject/libwebp,ya7lelkom/libwebp,Aexyn/libwebp,comoyo/gonzo-libwebp,Maria1099/webm.libwebp,altogother/webm.libwebp,imazen/libwebp,Maria1099/webm.libwebp,jacklicn/libwebp,kalli123/webm.libwebp,keane83/BLE_IM,redengineer/libwebp,appunite/libwebp,webmproject/libwebp,ya7lelkom/libwebp,Suvarna1488/webm.libwebp,keane83/BLE_IM,ttyangf/libwebp,altogother/webm.libwebp,comoyo/gonzo-libwebp,imazen/libwebp,reimaginemedia/webm.libwebp,gshORTON/webm.libwebp,rxl194/libwebp,kleopatra999/webm.libwebp,zofuthan/libwebp,yohunl/libwebp,redengineer/libwebp,appunite/libwebp,jacklicn/libwebp,yohunl/libwebp,comoyo/gonzo-libwebp,PKRoma/libwebp,imazen/libwebp,iniwf/webm.libwebp,ericmckean/webm.libwebp,webmproject/libwebp,Suvarna1488/webm.libwebp,jacklicn/libwebp,jiehu5114/libwebp,abwiz0086/webm.libwebp,zofuthan/libwebp,Acidburn0zzz/webm.libwebp,iniwf/webm.libwebp,kleopatra999/webm.libwebp,abwiz0086/webm.libwebp,Aexyn/libwebp,ttyangf/libwebp,Maria1099/webm.libwebp,Acidburn0zzz/webm.libwebp,kim42083/webm.libwebp