Use JavaAudioDeviceModule as default

Previously, we have created a Legacy ADM when no ADM is supplied.
With this change we will start creating a Java ADM instead.

The end goal is to make injection mandatory, and never creating ADMs.
This is one step on the way, and will allow us to clean up the Legacy
ADM code.

Bug: webrtc:7452
Change-Id: Ib99adc50346fe6b748f9435d2fc6321a50c3ee4e
Reviewed-on: https://webrtc-review.googlesource.com/c/123887
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Reviewed-by: Henrik Andreassson <henrika@webrtc.org>
Commit-Queue: Paulina Hensman <phensman@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26949}

sdk/android/native_unittests/application_context_provider.h

@@ -0,0 +1,23 @@
+/*
+ *  Copyright 2019 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#ifndef SDK_ANDROID_NATIVE_UNITTESTS_APPLICATION_CONTEXT_PROVIDER_H_
+#define SDK_ANDROID_NATIVE_UNITTESTS_APPLICATION_CONTEXT_PROVIDER_H_
+
+#include "sdk/android/src/jni/jni_helpers.h"
+
+namespace webrtc {
+namespace test {
+
+ScopedJavaLocalRef<jobject> GetAppContextForTest(JNIEnv* jni);
+
+}  // namespace test
+}  // namespace webrtc
+
+#endif  // SDK_ANDROID_NATIVE_UNITTESTS_APPLICATION_CONTEXT_PROVIDER_H_