Use enum class for injection constants

To improve code completion and error outputs from gtest, use enum class
for injection mode and injection result

Bug: none
Test: presubmit
Change-Id: I579a3da95c0d20375e155fd52d426e2460fdffa0
diff --git a/libs/input/android/os/InputEventInjectionSync.aidl b/libs/input/android/os/InputEventInjectionSync.aidl
new file mode 100644
index 0000000..95d24cb
--- /dev/null
+++ b/libs/input/android/os/InputEventInjectionSync.aidl
@@ -0,0 +1,36 @@
+/**
+ * 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.
+ */
+
+package android.os;
+
+/**
+ * Constants used to specify the input event injection synchronization mode.
+ *
+ * @hide
+ */
+@Backing(type="int")
+enum InputEventInjectionSync {
+    /* Injection is asynchronous and is assumed always to be successful. */
+    NONE = 0,
+
+    /* Waits for previous events to be dispatched so that the input dispatcher can determine
+     * whether input event injection willbe permitted based on the current input focus.
+     * Does not wait for the input event to finish processing. */
+    WAIT_FOR_RESULT = 1,
+
+    /* Waits for the input event to be completely processed. */
+    WAIT_FOR_FINISHED = 2,
+}