Break Layer class into Gl and Vulkan subclasses

Test: manual testing
Change-Id: Ibd2beed39de3ac6da7448e96496253cfe427dfbb
diff --git a/libs/hwui/VkLayer.h b/libs/hwui/VkLayer.h
new file mode 100644
index 0000000..353939f
--- /dev/null
+++ b/libs/hwui/VkLayer.h
@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "Layer.h"
+
+#include <SkSurface.h>
+
+namespace android {
+namespace uirenderer {
+/**
+ * A layer has dimensions and is backed by a VkImage.
+ */
+class VkLayer : public Layer {
+public:
+    VkLayer(RenderState& renderState, uint32_t layerWidth, uint32_t layerHeight)
+            : Layer(renderState, Api::Vulkan) {}
+
+    virtual ~VkLayer() {}
+
+    uint32_t getWidth() const override {
+        return mWidth;
+    }
+
+    uint32_t getHeight() const override {
+        return mHeight;
+    }
+
+    void setSize(uint32_t width, uint32_t height) override {
+        mWidth = width;
+        mHeight = height;
+    }
+
+    void setBlend(bool blend) override {
+        mBlend = blend;
+    }
+
+    bool isBlend() const override {
+        return mBlend;
+    }
+
+    sk_sp<SkSurface> getSurface() {
+        return mSurface;
+    }
+
+private:
+    int mWidth;
+    int mHeight;
+    bool mBlend;
+
+   sk_sp<SkSurface> mSurface;
+
+}; // struct VkLayer
+
+}; // namespace uirenderer
+}; // namespace android