Add an SkColorSpaceXformer image filter cache

The cache is scoped with the SkColorSpaceXformer object.

This ensures we're not transforming nodes with a degree > 1 multiple
times, and preserves the DAG topology.

Change-Id: I0b072cdac95f9f1c34e0565ed4f258aba986e1ae
Reviewed-on: https://skia-review.googlesource.com/21726
Commit-Queue: Florin Malita <fmalita@chromium.org>
Reviewed-by: Mike Reed <reed@google.com>
diff --git a/tests/QuickRejectTest.cpp b/tests/QuickRejectTest.cpp
index b705253..d7d330f 100644
--- a/tests/QuickRejectTest.cpp
+++ b/tests/QuickRejectTest.cpp
@@ -6,6 +6,7 @@
  */
 
 #include "SkArenaAlloc.h"
+#include "SkBitmap.h"
 #include "SkCanvas.h"
 #include "SkColorSpaceXformer.h"
 #include "SkDrawLooper.h"