CB-6460: Update license headers

src/wp/InAppBrowser.cs

@@ -1,4 +1,18 @@
-using System;
+/*
+	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.
+*/
+
+using System;
 using System.Diagnostics;
 using System.IO;
 using System.Runtime.Serialization;