SkGIFMovie: Fix corrupted background color
SkGIFMovie: Fix corrupted background color

The 'paintingColor' in onGetBitmap() was used to save the entire
gif's background color while filling the 1st frame of a gif image,
since it is 'static' qualified, so when re-entering this function
for subsequent frames, this saved value will be used directly without
re-obtaining it.
But if asynchronous playing multi gif files in single process without
being controlled, this 'static' will make the 'paintingColor'
corrupted, because the different SkGIFMovie instances hold the same
reference of 'paintingColor'.

Signed-off-by: Lu Tong <lu.x.tong@sonymobile.com>;

BUG=skia:

Review URL: https://codereview.chromium.org/1184083002

pcwalton/skia,ominux/skia,vanish87/skia,rubenvb/skia,aosp-mirror/platform_external_skia,Hikari-no-Tenshi/android_external_skia,qrealka/skia-hc,noselhq/skia,shahrzadmn/skia,shahrzadmn/skia,ominux/skia,google/skia,google/skia,qrealka/skia-hc,Hikari-no-Tenshi/android_external_skia,rubenvb/skia,noselhq/skia,vanish87/skia,nvoron23/skia,tmpvar/skia.cc,google/skia,nvoron23/skia,ominux/skia,google/skia,nvoron23/skia,google/skia,ominux/skia,ominux/skia,pcwalton/skia,vanish87/skia,HalCanary/skia-hc,shahrzadmn/skia,ominux/skia,todotodoo/skia,nvoron23/skia,pcwalton/skia,todotodoo/skia,rubenvb/skia,qrealka/skia-hc,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,aosp-mirror/platform_external_skia,Jichao/skia,tmpvar/skia.cc,nvoron23/skia,Jichao/skia,noselhq/skia,rubenvb/skia,vanish87/skia,nvoron23/skia,todotodoo/skia,HalCanary/skia-hc,noselhq/skia,Jichao/skia,tmpvar/skia.cc,rubenvb/skia,aosp-mirror/platform_external_skia,rubenvb/skia,aosp-mirror/platform_external_skia,nvoron23/skia,shahrzadmn/skia,rubenvb/skia,Jichao/skia,todotodoo/skia,todotodoo/skia,ominux/skia,qrealka/skia-hc,google/skia,Hikari-no-Tenshi/android_external_skia,pcwalton/skia,rubenvb/skia,rubenvb/skia,qrealka/skia-hc,tmpvar/skia.cc,todotodoo/skia,todotodoo/skia,Jichao/skia,todotodoo/skia,shahrzadmn/skia,pcwalton/skia,qrealka/skia-hc,tmpvar/skia.cc,vanish87/skia,google/skia,aosp-mirror/platform_external_skia,Hikari-no-Tenshi/android_external_skia,vanish87/skia,Hikari-no-Tenshi/android_external_skia,tmpvar/skia.cc,tmpvar/skia.cc,shahrzadmn/skia,tmpvar/skia.cc,noselhq/skia,ominux/skia,pcwalton/skia,Jichao/skia,aosp-mirror/platform_external_skia,google/skia,vanish87/skia,vanish87/skia,aosp-mirror/platform_external_skia,noselhq/skia,qrealka/skia-hc,noselhq/skia,HalCanary/skia-hc,rubenvb/skia,Hikari-no-Tenshi/android_external_skia,nvoron23/skia,vanish87/skia,pcwalton/skia,pcwalton/skia,HalCanary/skia-hc,noselhq/skia,Jichao/skia,ominux/skia,shahrzadmn/skia,tmpvar/skia.cc,qrealka/skia-hc,google/skia,aosp-mirror/platform_external_skia,todotodoo/skia,Jichao/skia,HalCanary/skia-hc,Jichao/skia,aosp-mirror/platform_external_skia,Hikari-no-Tenshi/android_external_skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,HalCanary/skia-hc,shahrzadmn/skia,pcwalton/skia,noselhq/skia,HalCanary/skia-hc,google/skia,HalCanary/skia-hc,shahrzadmn/skia,nvoron23/skia