Make real API for native code to get its window.

Added implementation to use ANativeWindow and provide
it to a NativeActivity.

Change-Id: I890d71b6e15d4af71e6cf81b327961d7061ec1c2
diff --git a/native/android/native_window.cpp b/native/android/native_window.cpp
new file mode 100644
index 0000000..7a6eb6d
--- /dev/null
+++ b/native/android/native_window.cpp
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2010 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 "Surface"
+#include <utils/Log.h>
+
+#include <android/native_window.h>
+#include <surfaceflinger/Surface.h>
+
+using android::Surface;
+
+static int32_t getWindowProp(ANativeWindow* window, int what) {
+    int value;
+    int res = window->query(window, what, &value);
+    return res < 0 ? res : value;
+}
+
+int32_t ANativeWindow_getWidth(ANativeWindow* window) {
+    return getWindowProp(window, NATIVE_WINDOW_WIDTH);
+}
+
+int32_t ANativeWindow_getHeight(ANativeWindow* window) {
+    return getWindowProp(window, NATIVE_WINDOW_HEIGHT);
+}
+
+int32_t ANativeWindow_getFormat(ANativeWindow* window) {
+    return getWindowProp(window, NATIVE_WINDOW_FORMAT);
+}