Container spec: clarify the background color field
Container spec: clarify the background color field

Change-Id: I03f634cbd147c2851eb06ddbc7b1014e04e21038

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