Fix potential off-by-one

Being consistent with the notion of mEndChildIndex, it should be -1 by
default. Otherwise it assumes the display list has a single element.
This is consistent with EndReorderBarrierDrawable constructor that would
set mEndChildIndex to -1 if display list is empty.

Bug: 117921091
Test: all tests should pass
Change-Id: I64b84c789ad8126ac8f0b8c2ebfc128635e5b30d
diff --git a/libs/hwui/pipeline/skia/ReorderBarrierDrawables.cpp b/libs/hwui/pipeline/skia/ReorderBarrierDrawables.cpp
index 5133bae..3b8caeb 100644
--- a/libs/hwui/pipeline/skia/ReorderBarrierDrawables.cpp
+++ b/libs/hwui/pipeline/skia/ReorderBarrierDrawables.cpp
@@ -27,7 +27,7 @@
 namespace skiapipeline {
 
 StartReorderBarrierDrawable::StartReorderBarrierDrawable(SkiaDisplayList* data)
-        : mEndChildIndex(0), mBeginChildIndex(data->mChildNodes.size()), mDisplayList(data) {}
+        : mEndChildIndex(-1), mBeginChildIndex(data->mChildNodes.size()), mDisplayList(data) {}
 
 void StartReorderBarrierDrawable::onDraw(SkCanvas* canvas) {
     if (mChildren.empty()) {