Add VTS readback tests for buffer slot clearing

Bug: 258196272
Test: atest VtsHalGraphicsComposer3_ReadbackTest
Test: atest VtsHalGraphicsComposerV2_2TargetTest
Change-Id: I95d24f9cf10d95e54bc228c02bedab9a8281cfd1
diff --git a/graphics/composer/aidl/vts/RenderEngineVts.cpp b/graphics/composer/aidl/vts/RenderEngineVts.cpp
index 66779c8..b84d0d0 100644
--- a/graphics/composer/aidl/vts/RenderEngineVts.cpp
+++ b/graphics/composer/aidl/vts/RenderEngineVts.cpp
@@ -76,18 +76,7 @@
 }
 
 void TestRenderEngine::checkColorBuffer(const std::vector<Color>& expectedColors) {
-    void* bufferData;
-    int32_t bytesPerPixel = -1;
-    int32_t bytesPerStride = -1;
-    ASSERT_EQ(0, mGraphicBuffer->lock(static_cast<uint32_t>(mGraphicBuffer->getUsage()),
-                                      &bufferData, &bytesPerPixel, &bytesPerStride));
-    const uint32_t stride = (bytesPerPixel > 0 && bytesPerStride > 0)
-                                    ? static_cast<uint32_t>(bytesPerStride / bytesPerPixel)
-                                    : mGraphicBuffer->getStride();
-    ReadbackHelper::compareColorBuffers(expectedColors, bufferData, stride,
-                                        mGraphicBuffer->getWidth(), mGraphicBuffer->getHeight(),
-                                        mFormat);
-    ASSERT_EQ(::android::OK, mGraphicBuffer->unlock());
+    ReadbackHelper::compareColorsToBuffer(expectedColors, mGraphicBuffer);
 }
 
 }  // namespace aidl::android::hardware::graphics::composer3::vts