Use correct color table for prior GIF frames

While investigating skbug.com/5883 I noticed that we use the color
table for the current frame even while recursively decoding frames that
the current frame depends on.

This CL updates fCurrColorTable, fCurrColorTableIsReal and fSwizzler
before decoding prior frames, and then sets them back afterwards.

Move telling the client about the color table into prepareToDecode,
since the other callers do not need to do so. (That is only necessary
for decoding to index 8, which is unsupported for frames with
dependencies.)

Add a test that exposes the bug. colorTables.gif has a local color
table in its second frame that does not match the global table used by
the first frame.

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4208

Change-Id: Id2dc9e3283adfd92801d2f38726afa74574b1955
Reviewed-on: https://skia-review.googlesource.com/4208
Reviewed-by: Joost Ouwerling <joostouwerling@google.com>
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>

1 files changed, 0 insertions, 0 deletions

diff --git a/resources/colorTables.gif b/resources/colorTables.gif
new file mode 100644
index 0000000000..f25d13cfaa
--- /dev/null
+++ b/resources/colorTables.gif