Fix fading edge effect from impacting neighboring pixels

Bug: 129117085
Test: skia unit tests and test cases described in the bug
Change-Id: Ieaa7c831dd6298ac0565e6f1837b1c1dbd4545da
diff --git a/libs/hwui/SkiaCanvas.cpp b/libs/hwui/SkiaCanvas.cpp
index 8340699..6ea6af8 100644
--- a/libs/hwui/SkiaCanvas.cpp
+++ b/libs/hwui/SkiaCanvas.cpp
@@ -26,6 +26,7 @@
 
 #include <SkAndroidFrameworkUtils.h>
 #include <SkAnimatedImage.h>
+#include <SkCanvasPriv.h>
 #include <SkCanvasStateUtils.h>
 #include <SkColorFilter.h>
 #include <SkDeque.h>
@@ -191,6 +192,18 @@
     return SkAndroidFrameworkUtils::SaveBehind(mCanvas, &bounds);
 }
 
+void SkiaCanvas::restoreUnclippedLayer(int restoreCount, const SkPaint& paint) {
+
+    while (mCanvas->getSaveCount() > restoreCount + 1) {
+        this->restore();
+    }
+
+    if (mCanvas->getSaveCount() == restoreCount + 1) {
+        SkCanvasPriv::DrawBehind(mCanvas, *filterPaint(paint));
+        this->restore();
+    }
+}
+
 class SkiaCanvas::Clip {
 public:
     Clip(const SkRect& rect, SkClipOp op, const SkMatrix& m)