test-hwc2: set layer blend mode

Test: Add "#define HAVE_NO_SURFACE_FLINGER" to
          frameworks/native/libs/gui/BufferQueueCore.cpp.
      Recompile and flash.
      Run "mm" in frameworks/native/services/surfaceflinger/tests/hwc2.
      Push test-hwc2 to device.
      Run "adb root && adb shell stop".
      Run test case. Ex: "./test-hwc2"

Change-Id: Id5a7a568fb81ac9aff388d04077a12765cc135a3
diff --git a/services/surfaceflinger/tests/hwc2/Hwc2TestLayer.h b/services/surfaceflinger/tests/hwc2/Hwc2TestLayer.h
index 9734ab8..a4d6d1d 100644
--- a/services/surfaceflinger/tests/hwc2/Hwc2TestLayer.h
+++ b/services/surfaceflinger/tests/hwc2/Hwc2TestLayer.h
@@ -33,11 +33,18 @@
 
     void reset();
 
+    hwc2_blend_mode_t  getBlendMode() const;
     hwc2_composition_t getComposition() const;
 
+    bool advanceBlendMode();
     bool advanceComposition();
 
 private:
+    std::array<Hwc2TestContainer*, 2> mProperties = {{
+        &mBlendMode, &mComposition
+    }};
+
+    Hwc2TestBlendMode mBlendMode;
     Hwc2TestComposition mComposition;
 };