Implement audio devices and streams HAL delegating to legacy HAL

Changes made to the .hal definition:

  - introduce Effect ID returned by the IEffectsFactory that
    needs to be passed to IStream.{add|remove}Effect; otherwise
    it's impossible to retrieve the underlying HAL effect handle;

  - change "bus address" in DeviceAddress to "string" type;

  - fix signature of some methods w.r.t. returning Result;

  - remove unused "struct AudioPatch".

Bug: 30222631
Test: make
Change-Id: Icb51729ef57bb2a5b0b78609735e7481bc04f95c
diff --git a/audio/2.0/default/Conversions.h b/audio/2.0/default/Conversions.h
new file mode 100644
index 0000000..ebda5c5
--- /dev/null
+++ b/audio/2.0/default/Conversions.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2016 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_hardware_audio_V2_0_Conversions_H_
+#define android_hardware_audio_V2_0_Conversions_H_
+
+#include <string>
+
+#include <android/hardware/audio/2.0/types.h>
+#include <system/audio.h>
+
+namespace android {
+namespace hardware {
+namespace audio {
+namespace V2_0 {
+namespace implementation {
+
+using ::android::hardware::audio::V2_0::DeviceAddress;
+
+std::string deviceAddressToHal(const DeviceAddress& address);
+
+}  // namespace implementation
+}  // namespace V2_0
+}  // namespace audio
+}  // namespace hardware
+}  // namespace android
+
+#endif  // android_hardware_audio_V2_0_Conversions_H_