Add file headers

Author: Ferry Spiering

packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/Constants.java

@@ -1,3 +1,7 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
 package io.flutter.plugins.webviewflutter;
 
 public class Constants {

packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FileChooserActivity.java

@@ -1,3 +1,7 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
 package io.flutter.plugins.webviewflutter;
 
 import android.app.Activity;

packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FileChooserLauncher.java

@@ -1,3 +1,7 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
 package io.flutter.plugins.webviewflutter;
 
 import android.Manifest;

packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/GenericFileProvider.java

@@ -1,3 +1,7 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
 package io.flutter.plugins.webviewflutter;
 
 import androidx.core.content.FileProvider;

packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/RequestCameraPermissionActivity.java

@@ -1,3 +1,7 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
 package io.flutter.plugins.webviewflutter;
 
 import android.Manifest;