Chromecast: unmute audio stream on Cast session finish on pre-M devices.

chromecast/browser/android/apk/src/org/chromium/chromecast/shell/CastAudioManager.java

Index: chromecast/browser/android/apk/src/org/chromium/chromecast/shell/CastAudioManager.java
diff --git a/chromecast/browser/android/apk/src/org/chromium/chromecast/shell/CastAudioManager.java b/chromecast/browser/android/apk/src/org/chromium/chromecast/shell/CastAudioManager.java
new file mode 100644
index 0000000000000000000000000000000000000000..cc5b46e7a59f9584b027134d393e10705ee02baa
--- /dev/null
+++ b/chromecast/browser/android/apk/src/org/chromium/chromecast/shell/CastAudioManager.java
@@ -0,0 +1,25 @@
+// Copyright 2015 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 org.chromium.chromecast.shell;
+
+import android.content.Context;
+import android.media.AudioManager;
+
+/**
+ * Wrapper for Cast code to use a single AudioManager instance.
+ * Muting and unmuting streams must be invoke on the same AudioManager instance.
+ */
+public class CastAudioManager {
+
+    private static AudioManager sAudioManager = null;
+
+    public static AudioManager getAudioManager(Context context) {
+        if (sAudioManager == null) {
+            sAudioManager = (AudioManager) context.getApplicationContext()
+                .getSystemService(Context.AUDIO_SERVICE);
+        }
+        return sAudioManager;
+    }
+}