[Chromecast] Turn CastContentWindow into an abstract interface.

chromecast/browser/android/jni_registrar.h

Index: chromecast/browser/android/jni_registrar.h
diff --git a/chromecast/browser/android/jni_registrar.h b/chromecast/browser/android/jni_registrar.h
new file mode 100644
index 0000000000000000000000000000000000000000..9d6a80d0a7e616911b3ffdd0daa3dbf594d637b7
--- /dev/null
+++ b/chromecast/browser/android/jni_registrar.h
@@ -0,0 +1,19 @@
+// Copyright 2016 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.
+
+#ifndef CHROMECAST_BROWSER_ANDROID_JNI_REGISTRAR_H_
+#define CHROMECAST_BROWSER_ANDROID_JNI_REGISTRAR_H_
+
+#include <jni.h>
+
+namespace chromecast {
+namespace shell {
+
+// Register all JNI bindings necessary for the Android cast shell.
+bool RegisterJni(JNIEnv* env);
+
+}  // namespace shell
+}  // namespace chromecast
+
+#endif  // CHROMECAST_BROWSER_ANDROID_JNI_REGISTRAR_H_