test-hwc2: set layer plane alpha

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: I48146953f745dc650ead5a6e9d6f456cf5a9d7ef
diff --git a/services/surfaceflinger/tests/hwc2/Hwc2TestLayer.h b/services/surfaceflinger/tests/hwc2/Hwc2TestLayer.h
index b07fe7b..5ba2cfc 100644
--- a/services/surfaceflinger/tests/hwc2/Hwc2TestLayer.h
+++ b/services/surfaceflinger/tests/hwc2/Hwc2TestLayer.h
@@ -36,19 +36,22 @@
     hwc2_blend_mode_t      getBlendMode() const;
     hwc2_composition_t     getComposition() const;
     android_dataspace_t    getDataspace() const;
+    float                  getPlaneAlpha() const;
 
     bool advanceBlendMode();
     bool advanceComposition();
     bool advanceDataspace();
+    bool advancePlaneAlpha();
 
 private:
-    std::array<Hwc2TestContainer*, 3> mProperties = {{
-        &mBlendMode, &mComposition, &mDataspace
+    std::array<Hwc2TestContainer*, 4> mProperties = {{
+        &mBlendMode, &mComposition, &mDataspace, &mPlaneAlpha
     }};
 
     Hwc2TestBlendMode mBlendMode;
     Hwc2TestComposition mComposition;
     Hwc2TestDataspace mDataspace;
+    Hwc2TestPlaneAlpha mPlaneAlpha;
 };
 
 #endif /* ifndef _HWC2_TEST_LAYER_H */