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/jni-base.cc b/utils/java/jni-base.cc
new file mode 100644
index 0000000..8073c5a
--- /dev/null
+++ b/utils/java/jni-base.cc
@@ -0,0 +1,71 @@
+/*
+ * 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.
+ */
+
+#include "utils/java/jni-base.h"
+
+#include <jni.h>
+#include <type_traits>
+#include <vector>
+
+#include "utils/base/integral_types.h"
+#include "utils/java/scoped_local_ref.h"
+#include "utils/java/string_utils.h"
+#include "utils/memory/mmap.h"
+
+using libtextclassifier3::JStringToUtf8String;
+using libtextclassifier3::ScopedLocalRef;
+
+namespace libtextclassifier3 {
+
+std::string ToStlString(JNIEnv* env, const jstring& str) {
+  std::string result;
+  JStringToUtf8String(env, str, &result);
+  return result;
+}
+
+jint GetFdFromAssetFileDescriptor(JNIEnv* env, jobject afd) {
+  // Get system-level file descriptor from AssetFileDescriptor.
+  ScopedLocalRef<jclass> afd_class(
+      env->FindClass("android/content/res/AssetFileDescriptor"), env);
+  if (afd_class == nullptr) {
+    TC3_LOG(ERROR) << "Couldn't find AssetFileDescriptor.";
+    return reinterpret_cast<jlong>(nullptr);
+  }
+  jmethodID afd_class_getFileDescriptor = env->GetMethodID(
+      afd_class.get(), "getFileDescriptor", "()Ljava/io/FileDescriptor;");
+  if (afd_class_getFileDescriptor == nullptr) {
+    TC3_LOG(ERROR) << "Couldn't find getFileDescriptor.";
+    return reinterpret_cast<jlong>(nullptr);
+  }
+
+  ScopedLocalRef<jclass> fd_class(env->FindClass("java/io/FileDescriptor"),
+                                  env);
+  if (fd_class == nullptr) {
+    TC3_LOG(ERROR) << "Couldn't find FileDescriptor.";
+    return reinterpret_cast<jlong>(nullptr);
+  }
+  jfieldID fd_class_descriptor =
+      env->GetFieldID(fd_class.get(), "descriptor", "I");
+  if (fd_class_descriptor == nullptr) {
+    TC3_LOG(ERROR) << "Couldn't find descriptor.";
+    return reinterpret_cast<jlong>(nullptr);
+  }
+
+  jobject bundle_jfd = env->CallObjectMethod(afd, afd_class_getFileDescriptor);
+  return env->GetIntField(bundle_jfd, fd_class_descriptor);
+}
+
+}  // namespace libtextclassifier3