Factorize code for clearing HtreeGroup.
Factorize code for clearing HtreeGroup.

Change-Id: I29de6dab7383b8cf071eec155e01340d5fdadee5

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