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/DevicesFactory.h b/audio/2.0/default/DevicesFactory.h
new file mode 100644
index 0000000..0ea9859
--- /dev/null
+++ b/audio/2.0/default/DevicesFactory.h
@@ -0,0 +1,59 @@
+/*
+ * 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 HIDL_GENERATED_android_hardware_audio_V2_0_DevicesFactory_H_
+#define HIDL_GENERATED_android_hardware_audio_V2_0_DevicesFactory_H_
+
+#include <hardware/audio.h>
+
+#include <android/hardware/audio/2.0/IDevicesFactory.h>
+#include <hidl/Status.h>
+
+#include <hidl/MQDescriptor.h>
+namespace android {
+namespace hardware {
+namespace audio {
+namespace V2_0 {
+namespace implementation {
+
+using ::android::hardware::audio::V2_0::IDevice;
+using ::android::hardware::audio::V2_0::IDevicesFactory;
+using ::android::hardware::audio::V2_0::Result;
+using ::android::hardware::Return;
+using ::android::hardware::Void;
+using ::android::hardware::hidl_vec;
+using ::android::hardware::hidl_string;
+using ::android::sp;
+
+struct DevicesFactory : public IDevicesFactory {
+    // Methods from ::android::hardware::audio::V2_0::IDevicesFactory follow.
+    Return<void> openDevice(IDevicesFactory::Device device, openDevice_cb _hidl_cb)  override;
+
+  private:
+    static const char* deviceToString(IDevicesFactory::Device device);
+    static int loadAudioInterface(const char *if_name, audio_hw_device_t **dev);
+
+};
+
+extern "C" IDevicesFactory* HIDL_FETCH_IDevicesFactory(const char* name);
+
+}  // namespace implementation
+}  // namespace V2_0
+}  // namespace audio
+}  // namespace hardware
+}  // namespace android
+
+#endif  // HIDL_GENERATED_android_hardware_audio_V2_0_DevicesFactory_H_