Removes usage of native base::android::GetApplicationContext()

webrtc/base/java/src/org/webrtc/ContextUtils.java

+/*
+ *  Copyright 2017 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.
+ */
+
+package org.webrtc;
+
+import android.content.Context;
+
+/**
+ * Class for storing the application context and retrieving it in a static context.
+ */
+public class ContextUtils {
+  private static Context applicationContext;
+
+  public static void initialize(Context applicationContext) {
+    ContextUtils.applicationContext = applicationContext;
+  }
+
+  public static Context getApplicationContext() {
+    return applicationContext;
+  }
+}