Adds default (mock) Context Hub HAL 1.2 impl

Also refactors common code.

Bug: 166845383
Test: Compile only (VTS test coming up in future CL)
Change-Id: Iae6cf09e2fffb854af61c29e6004ceb062a892b3
diff --git a/contexthub/1.2/default/service.cpp b/contexthub/1.2/default/service.cpp
new file mode 100644
index 0000000..41cb753
--- /dev/null
+++ b/contexthub/1.2/default/service.cpp
@@ -0,0 +1,42 @@
+/*
+ * 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.
+ */
+
+#define LOG_TAG "android.hardware.contexthub@1.2-service"
+
+#include <android/hardware/contexthub/1.2/IContexthub.h>
+#include <hidl/HidlTransportSupport.h>
+#include <log/log.h>
+#include <utils/StrongPointer.h>
+#include "Contexthub.h"
+
+using ::android::hardware::configureRpcThreadpool;
+using ::android::hardware::joinRpcThreadpool;
+using ::android::hardware::contexthub::V1_2::IContexthub;
+using ::android::hardware::contexthub::V1_2::implementation::Contexthub;
+
+int main() {
+    configureRpcThreadpool(1, true /* callerWillJoin */);
+
+    ::android::sp<IContexthub> contexthub = new Contexthub();
+    if (contexthub->registerAsService() != ::android::OK) {
+        ALOGE("Failed to register Contexthub HAL instance");
+        return 1;
+    }
+
+    joinRpcThreadpool();
+    ALOGE("Service exited");
+    return 1;
+}