Fix a crash in skia pipeline, when empty reorder block is first

Fix a crash in skia pipeline, which happens if an empty reorder
barrier is inserted at index 0 in a SkiaDisplayList.
Add a unit test that repro the bug (unit test is crashing wihtout
the fix and passing with the fix).

Test: built and ran skia pipeline with angler-eng and run HWUI unit
tests.

Change-Id: I4aded15021c70cc0ae8daa83bbe8ed0e10a41eef

1 files changed, 1 insertions, 1 deletions

diff --git a/libs/hwui/pipeline/skia/ReorderBarrierDrawables.cpp b/libs/hwui/pipeline/skia/ReorderBarrierDrawables.cpp
index 6973209c4626..d05e7f660c72 100644
--- a/libs/hwui/pipeline/skia/ReorderBarrierDrawables.cpp
+++ b/libs/hwui/pipeline/skia/ReorderBarrierDrawables.cpp
@@ -40,7 +40,7 @@ void StartReorderBarrierDrawable::onDraw(SkCanvas* canvas) {
         //mChildren is allocated and initialized only the first time onDraw is called and cached for
         //subsequent calls
         mChildren.reserve(mEndChildIndex - mBeginChildIndex + 1);
-        for (unsigned int i = mBeginChildIndex; i <= mEndChildIndex; i++) {
+        for (int i = mBeginChildIndex; i <= mEndChildIndex; i++) {
             mChildren.push_back(const_cast<RenderNodeDrawable*>(&mDisplayList->mChildNodes[i]));
         }
     }