Add hostgraphics classes required for ImageReader

Bug: 117921091
Test: all tests should pass
Change-Id: I5d60a1177d43eb8dec08403cf34936007b8a267f
(cherry picked from commit c1409f44f82313902a690fb257ee271dc16385a0)
diff --git a/libs/hostgraphics/gui/ConsumerBase.h b/libs/hostgraphics/gui/ConsumerBase.h
new file mode 100644
index 0000000..9002953
--- /dev/null
+++ b/libs/hostgraphics/gui/ConsumerBase.h
@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2019 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.
+ */
+
+#ifndef ANDROID_GUI_CONSUMERBASE_H
+#define ANDROID_GUI_CONSUMERBASE_H
+
+#include <gui/BufferItem.h>
+
+#include <utils/RefBase.h>
+
+namespace android {
+
+class ConsumerBase : public virtual RefBase {
+public:
+    struct FrameAvailableListener : public virtual RefBase {
+        // See IConsumerListener::onFrame{Available,Replaced}
+        virtual void onFrameAvailable(const BufferItem& item) = 0;
+        virtual void onFrameReplaced(const BufferItem& /* item */) {}
+    };
+};
+
+} // namespace android
+
+#endif // ANDROID_GUI_CONSUMERBASE_H
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