SkDiscardablePixelRef should favor not decoding to YUV if they already decoded to RGB.
SkDiscardablePixelRef should favor not decoding to YUV if they already decoded to RGB.

BUG=skia:
BUG=459760

Review URL: https://codereview.chromium.org/944823004

pcwalton/skia,OneRom/external_skia,PAC-ROM/android_external_skia,tmpvar/skia.cc,TeamExodus/external_skia,aosp-mirror/platform_external_skia,todotodoo/skia,invisiblek/android_external_skia,AOSP-YU/platform_external_skia,google/skia,UBERMALLOW/external_skia,MarshedOut/android_external_skia,invisiblek/android_external_skia,pcwalton/skia,pcwalton/skia,nfxosp/platform_external_skia,samuelig/skia,MonkeyZZZZ/platform_external_skia,noselhq/skia,aosp-mirror/platform_external_skia,shahrzadmn/skia,Infinitive-OS/platform_external_skia,pcwalton/skia,AOSP-YU/platform_external_skia,tmpvar/skia.cc,nvoron23/skia,vanish87/skia,HalCanary/skia-hc,todotodoo/skia,AOSPB/external_skia,Igalia/skia,noselhq/skia,nfxosp/platform_external_skia,aosp-mirror/platform_external_skia,nfxosp/platform_external_skia,PAC-ROM/android_external_skia,Hikari-no-Tenshi/android_external_skia,noselhq/skia,HalCanary/skia-hc,MarshedOut/android_external_skia,nvoron23/skia,MonkeyZZZZ/platform_external_skia,MinimalOS-AOSP/platform_external_skia,timduru/platform-external-skia,OneRom/external_skia,MarshedOut/android_external_skia,YUPlayGodDev/platform_external_skia,invisiblek/android_external_skia,vanish87/skia,noselhq/skia,amyvmiwei/skia,AOSPB/external_skia,MonkeyZZZZ/platform_external_skia,UBERMALLOW/external_skia,MonkeyZZZZ/platform_external_skia,VRToxin-AOSP/android_external_skia,samuelig/skia,Infinitive-OS/platform_external_skia,MonkeyZZZZ/platform_external_skia,AOSP-YU/platform_external_skia,PAC-ROM/android_external_skia,TeamExodus/external_skia,TeamExodus/external_skia,Igalia/skia,AOSP-YU/platform_external_skia,invisiblek/android_external_skia,samuelig/skia,TeamTwisted/external_skia,amyvmiwei/skia,YUPlayGodDev/platform_external_skia,BrokenROM/external_skia,TeamExodus/external_skia,TeamTwisted/external_skia,rubenvb/skia,BrokenROM/external_skia,invisiblek/android_external_skia,w3nd1go/android_external_skia,boulzordev/android_external_skia,Jichao/skia,MinimalOS-AOSP/platform_external_skia,YUPlayGodDev/platform_external_skia,boulzordev/android_external_skia,HalCanary/skia-hc,AOSPB/external_skia,vanish87/skia,UBERMALLOW/external_skia,MonkeyZZZZ/platform_external_skia,Infinitive-OS/platform_external_skia,PAC-ROM/android_external_skia,TeamExodus/external_skia,google/skia,HalCanary/skia-hc,YUPlayGodDev/platform_external_skia,w3nd1go/android_external_skia,todotodoo/skia,rubenvb/skia,pcwalton/skia,timduru/platform-external-skia,HalCanary/skia-hc,Igalia/skia,MinimalOS-AOSP/platform_external_skia,aosp-mirror/platform_external_skia,geekboxzone/mmallow_external_skia,Infinitive-OS/platform_external_skia,TeamTwisted/external_skia,pcwalton/skia,OneRom/external_skia,MarshedOut/android_external_skia,rubenvb/skia,ominux/skia,todotodoo/skia,qrealka/skia-hc,shahrzadmn/skia,ominux/skia,timduru/platform-external-skia,google/skia,geekboxzone/mmallow_external_skia,pcwalton/skia,AOSP-YU/platform_external_skia,aosp-mirror/platform_external_skia,qrealka/skia-hc,timduru/platform-external-skia,rubenvb/skia,UBERMALLOW/external_skia,nfxosp/platform_external_skia,PAC-ROM/android_external_skia,vanish87/skia,w3nd1go/android_external_skia,nfxosp/platform_external_skia,w3nd1go/android_external_skia,nfxosp/platform_external_skia,Jichao/skia,AOSP-YU/platform_external_skia,Jichao/skia,nvoron23/skia,MonkeyZZZZ/platform_external_skia,HalCanary/skia-hc,ominux/skia,Igalia/skia,TeamTwisted/external_skia,ominux/skia,boulzordev/android_external_skia,shahrzadmn/skia,spezi77/android_external_skia,tmpvar/skia.cc,samuelig/skia,Jichao/skia,rubenvb/skia,geekboxzone/mmallow_external_skia,geekboxzone/mmallow_external_skia,Infinitive-OS/platform_external_skia,google/skia,MinimalOS-AOSP/platform_external_skia,tmpvar/skia.cc,ominux/skia,YUPlayGodDev/platform_external_skia,Hikari-no-Tenshi/android_external_skia,HalCanary/skia-hc,MarshedOut/android_external_skia,google/skia,nvoron23/skia,VRToxin-AOSP/android_external_skia,MinimalOS-AOSP/platform_external_skia,TeamTwisted/external_skia,UBERMALLOW/external_skia,YUPlayGodDev/platform_external_skia,ominux/skia,qrealka/skia-hc,noselhq/skia,nvoron23/skia,ominux/skia,PAC-ROM/android_external_skia,todotodoo/skia,OneRom/external_skia,Hikari-no-Tenshi/android_external_skia,OneRom/external_skia,qrealka/skia-hc,rubenvb/skia,spezi77/android_external_skia,amyvmiwei/skia,spezi77/android_external_skia,nvoron23/skia,PAC-ROM/android_external_skia,UBERMALLOW/external_skia,shahrzadmn/skia,rubenvb/skia,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,vanish87/skia,geekboxzone/mmallow_external_skia,pcwalton/skia,qrealka/skia-hc,VRToxin-AOSP/android_external_skia,MonkeyZZZZ/platform_external_skia,VRToxin-AOSP/android_external_skia,nvoron23/skia,vanish87/skia,samuelig/skia,MinimalOS-AOSP/platform_external_skia,AOSPB/external_skia,spezi77/android_external_skia,boulzordev/android_external_skia,w3nd1go/android_external_skia,boulzordev/android_external_skia,MarshedOut/android_external_skia,UBERMALLOW/external_skia,w3nd1go/android_external_skia,AOSP-YU/platform_external_skia,UBERMALLOW/external_skia,google/skia,noselhq/skia,timduru/platform-external-skia,Infinitive-OS/platform_external_skia,samuelig/skia,OneRom/external_skia,Hikari-no-Tenshi/android_external_skia,TeamExodus/external_skia,shahrzadmn/skia,rubenvb/skia,qrealka/skia-hc,TeamExodus/external_skia,HalCanary/skia-hc,VRToxin-AOSP/android_external_skia,w3nd1go/android_external_skia,todotodoo/skia,UBERMALLOW/external_skia,nvoron23/skia,MinimalOS-AOSP/platform_external_skia,w3nd1go/android_external_skia,YUPlayGodDev/platform_external_skia,MarshedOut/android_external_skia,OneRom/external_skia,AOSPB/external_skia,aosp-mirror/platform_external_skia,noselhq/skia,qrealka/skia-hc,VRToxin-AOSP/android_external_skia,shahrzadmn/skia,VRToxin-AOSP/android_external_skia,timduru/platform-external-skia,geekboxzone/mmallow_external_skia,TeamExodus/external_skia,AOSPB/external_skia,TeamTwisted/external_skia,amyvmiwei/skia,Hikari-no-Tenshi/android_external_skia,BrokenROM/external_skia,nfxosp/platform_external_skia,timduru/platform-external-skia,MonkeyZZZZ/platform_external_skia,spezi77/android_external_skia,rubenvb/skia,Jichao/skia,Jichao/skia,VRToxin-AOSP/android_external_skia,aosp-mirror/platform_external_skia,Infinitive-OS/platform_external_skia,invisiblek/android_external_skia,boulzordev/android_external_skia,Jichao/skia,YUPlayGodDev/platform_external_skia,MinimalOS-AOSP/platform_external_skia,OneRom/external_skia,w3nd1go/android_external_skia,TeamExodus/external_skia,nfxosp/platform_external_skia,AOSP-YU/platform_external_skia,YUPlayGodDev/platform_external_skia,AOSP-YU/platform_external_skia,qrealka/skia-hc,BrokenROM/external_skia,shahrzadmn/skia,tmpvar/skia.cc,geekboxzone/mmallow_external_skia,boulzordev/android_external_skia,TeamTwisted/external_skia,invisiblek/android_external_skia,Jichao/skia,boulzordev/android_external_skia,Hikari-no-Tenshi/android_external_skia,MarshedOut/android_external_skia,aosp-mirror/platform_external_skia,Infinitive-OS/platform_external_skia,tmpvar/skia.cc,amyvmiwei/skia,aosp-mirror/platform_external_skia,TeamTwisted/external_skia,nfxosp/platform_external_skia,Igalia/skia,AOSPB/external_skia,Igalia/skia,BrokenROM/external_skia,Hikari-no-Tenshi/android_external_skia,Infinitive-OS/platform_external_skia,samuelig/skia,todotodoo/skia,nvoron23/skia,invisiblek/android_external_skia,vanish87/skia,VRToxin-AOSP/android_external_skia,BrokenROM/external_skia,tmpvar/skia.cc,google/skia,HalCanary/skia-hc,vanish87/skia,spezi77/android_external_skia,AOSPB/external_skia,PAC-ROM/android_external_skia,TeamTwisted/external_skia,ominux/skia,geekboxzone/mmallow_external_skia,MinimalOS-AOSP/platform_external_skia,MarshedOut/android_external_skia,todotodoo/skia,AOSPB/external_skia,google/skia,amyvmiwei/skia,rubenvb/skia,noselhq/skia,amyvmiwei/skia,google/skia,boulzordev/android_external_skia,shahrzadmn/skia,todotodoo/skia,BrokenROM/external_skia,tmpvar/skia.cc,BrokenROM/external_skia,Igalia/skia,vanish87/skia,tmpvar/skia.cc,ominux/skia,google/skia,OneRom/external_skia,geekboxzone/mmallow_external_skia,pcwalton/skia,Igalia/skia,shahrzadmn/skia,noselhq/skia,samuelig/skia,amyvmiwei/skia,PAC-ROM/android_external_skia,aosp-mirror/platform_external_skia,Jichao/skia