Set isOpaque For BlendMode::None

Test: atest VtsHalGraphicsComposer3_TargetTest
BUG: 216205298
BUG: 219576457

Change-Id: I479d8367e5abf8893b94ac64b7149a2f0e4cf75b
diff --git a/graphics/composer/aidl/vts/ReadbackVts.cpp b/graphics/composer/aidl/vts/ReadbackVts.cpp
index 03b1b6c..abb58e2 100644
--- a/graphics/composer/aidl/vts/ReadbackVts.cpp
+++ b/graphics/composer/aidl/vts/ReadbackVts.cpp
@@ -76,6 +76,7 @@
 
     layerSettings.alpha = ::android::half(mAlpha);
     layerSettings.disableBlending = mBlendMode == BlendMode::NONE;
+    layerSettings.source.buffer.isOpaque = mBlendMode == BlendMode::NONE;
     layerSettings.geometry.boundaries = ::android::FloatRect(
             static_cast<float>(mDisplayFrame.left), static_cast<float>(mDisplayFrame.top),
             static_cast<float>(mDisplayFrame.right), static_cast<float>(mDisplayFrame.bottom));