drm_hwcomposer: refactor platform directory

Motivation:

Platform term meaning used in drm_hwcomposer does not correspond to the
content of the platform directory. Platform directory consists of:
1. Buffer information getters for different gralloc (currently called platform).
2. Composition planner logic (which has flaws and should be reworked into
   layer->plane mapping during validation stage logic).
3. DrmGenericImpoter with reference counting logic.

Android-11 IMapper@4 metadata API offers a generic way to access buffer
information which makes other gralloc buffer information getters obsolete.
Legacy getters should be maintained for some time until all known users
will migrate to Mapper@4 API.

Implementation:

1. Split 'PlatformImporter' logic to 'Importer' only and 'Buffer Getter' logic.
   a. Remove buffer_handle_t parameter from ImportBuffer(). Instead user should
      get BufferInfo using ConvertBoInfo to struct hwc_drm_bo_t, then use it for
      ImportBuffer().
   b. Move DrmGenericImporter.{cpp/h} into the drm directory.

2. Isolate planner code in single file and move it to compositor directory as
   compositor/Planner.{cpp/h}

3. Rename platform definition
   a. Rename platform directory to bufferinfo.
   b. Rename/move bufferinfo/platorm*.{cpp,h} getters to
      bufferinfo/legacy/BufferInfo*.{cpp,h}. Align class names/includes.

4. Split legacy/metadata getters logic.
   a. Apply existing bufferinfogetter base class only for legacy getters.
   b. Combine legacy/generic gettera under new base class.
   c. Create a placeholder for generic(metadata) getter.

Signed-off-by: Roman Stratiienko <r.stratiienko@gmail.com>
diff --git a/drm/DrmGenericImporter.h b/drm/DrmGenericImporter.h
new file mode 100644
index 0000000..efda6be
--- /dev/null
+++ b/drm/DrmGenericImporter.h
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2020 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_PLATFORM_DRM_GENERIC_H_
+#define ANDROID_PLATFORM_DRM_GENERIC_H_
+
+#include <drm/drm_fourcc.h>
+#include <hardware/gralloc.h>
+
+#include <map>
+
+#include "drm/DrmDevice.h"
+#include "drmhwcgralloc.h"
+
+#ifndef DRM_FORMAT_INVALID
+#define DRM_FORMAT_INVALID 0
+#endif
+
+namespace android {
+
+class Importer {
+ public:
+  virtual ~Importer() {
+  }
+
+  // Imports the buffer referred to by handle into bo.
+  //
+  // Note: This can be called from a different thread than ReleaseBuffer. The
+  //       implementation is responsible for ensuring thread safety.
+  virtual int ImportBuffer(hwc_drm_bo_t *bo) = 0;
+
+  // Releases the buffer object (ie: does the inverse of ImportBuffer)
+  //
+  // Note: This can be called from a different thread than ImportBuffer. The
+  //       implementation is responsible for ensuring thread safety.
+  virtual int ReleaseBuffer(hwc_drm_bo_t *bo) = 0;
+};
+
+class DrmGenericImporter : public Importer {
+ public:
+  DrmGenericImporter(DrmDevice *drm);
+  ~DrmGenericImporter() override;
+
+  int ImportBuffer(hwc_drm_bo_t *bo) override;
+  int ReleaseBuffer(hwc_drm_bo_t *bo) override;
+  int ImportHandle(uint32_t gem_handle);
+  int ReleaseHandle(uint32_t gem_handle);
+
+ protected:
+  DrmDevice *drm_;
+
+ private:
+  int CloseHandle(uint32_t gem_handle);
+  std::map<uint32_t, int> gem_refcount_;
+};
+
+}  // namespace android
+
+#endif