Add InputReporter interface to InputDispatcher

This adds a new library to inputflinger, libinputreporter, that handles
events reported from InputDispatcher.

The CL makes InputDispatcher notify InputReporter for two events:
- Unhandled Keys: Keys that were not handled by the system or apps. A key
event is unhandled if:
   - The event was not handled and there is no fallback key; or
   - The event was not handled and it has a fallback key,
       but the fallback key was not handled.
- Dropped Keys: Key events can be dropped for several reasons, which
can be seen in InputReporter::DropReason.

Currently, the default implementation of InputReporter does nothing when
it recieves a dropped or unhandled key notification. The InputReporter
is created via its factory method, createInputReporter().

Bug: 119312287
Test: manual: Build, and verify using log output
Change-Id: I90ac525d648bb75e0bc8532f68f6a9e4ab51d54b
diff --git a/services/inputflinger/InputReporter.cpp b/services/inputflinger/InputReporter.cpp
new file mode 100644
index 0000000..cf4220f
--- /dev/null
+++ b/services/inputflinger/InputReporter.cpp
@@ -0,0 +1,35 @@
+/*
+ * 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 "InputReporter.h"
+
+namespace android {
+
+// --- InputReporter ---
+
+void InputReporter::reportUnhandledKey(uint32_t sequenceNum) {
+  // do nothing
+}
+
+void InputReporter::reportDroppedKey(uint32_t sequenceNum) {
+  // do nothing
+}
+
+sp<InputReporter> createInputReporter() {
+  return new InputReporter();
+}
+
+} // namespace android