Export lib3 to AOSP (external/libtextclassifier part)

1. Include both annotator (existing one) and actions(new one for smart
   reply and actions)
2. One more model file. actions_suggestions.model is dropped to
  /etc/textclassifier./ It is around 7.5mb for now, we will slim down
  it later.
3. The Java counterpart of the JNI is now moved from frameworks/base
   to here.

Test: atest android.view.textclassifier.TextClassificationManagerTest

Change-Id: Icb2458967ef51efa2952b3eaddefbf1f7b359930
diff --git a/utils/java/scoped_global_ref.h b/utils/java/scoped_global_ref.h
new file mode 100644
index 0000000..de0608e
--- /dev/null
+++ b/utils/java/scoped_global_ref.h
@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2018 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 LIBTEXTCLASSIFIER_UTILS_JAVA_SCOPED_GLOBAL_REF_H_
+#define LIBTEXTCLASSIFIER_UTILS_JAVA_SCOPED_GLOBAL_REF_H_
+
+#include <jni.h>
+#include <memory>
+#include <type_traits>
+
+#include "utils/base/logging.h"
+
+namespace libtextclassifier3 {
+
+// A deleter to be used with std::unique_ptr to delete JNI global references.
+class GlobalRefDeleter {
+ public:
+  GlobalRefDeleter() : jvm_(nullptr) {}
+
+  // Style guide violating implicit constructor so that the GlobalRefDeleter
+  // is implicitly constructed from the second argument to ScopedGlobalRef.
+  GlobalRefDeleter(JavaVM* jvm) : jvm_(jvm) {}  // NOLINT(runtime/explicit)
+
+  GlobalRefDeleter(const GlobalRefDeleter& orig) = default;
+
+  // Copy assignment to allow move semantics in ScopedGlobalRef.
+  GlobalRefDeleter& operator=(const GlobalRefDeleter& rhs) {
+    TC3_CHECK_EQ(jvm_, rhs.jvm_);
+    return *this;
+  }
+
+  // The delete operator.
+  void operator()(jobject object) const {
+    JNIEnv* env;
+    if (object != nullptr && jvm_ != nullptr &&
+        JNI_OK ==
+            jvm_->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_4)) {
+      env->DeleteGlobalRef(object);
+    }
+  }
+
+ private:
+  // The jvm_ stashed to use for deletion.
+  JavaVM* const jvm_;
+};
+
+// A smart pointer that deletes a JNI global reference when it goes out
+// of scope. Usage is:
+// ScopedGlobalRef<jobject> scoped_global(env->JniFunction(), jvm);
+template <typename T>
+using ScopedGlobalRef =
+    std::unique_ptr<typename std::remove_pointer<T>::type, GlobalRefDeleter>;
+
+// A helper to create global references. Assumes the object has a local
+// reference, which it deletes.
+template <typename T>
+ScopedGlobalRef<T> MakeGlobalRef(T object, JNIEnv* env, JavaVM* jvm) {
+  const jobject global_object = env->NewGlobalRef(object);
+  env->DeleteLocalRef(object);
+  return ScopedGlobalRef<T>(reinterpret_cast<T>(global_object), jvm);
+}
+
+}  // namespace libtextclassifier3
+
+#endif  // LIBTEXTCLASSIFIER_UTILS_JAVA_SCOPED_GLOBAL_REF_H_