91f0baa898
Part 1/2: individual static helpers for managing listeners, more to come to encompass all functionality inside one class. Implement utility classes for: - storing information about a listener containing callback and Executor to use (see ListenerInfo class) - managing listeners in a list: remove / retrieve / check presence of a listener in a given list (see removeListener / getListenerInfo / hasListener methods) - managing listeners in a list, while managing the lifecycle of the list, and associated stub for receiving events (for instance for AudioManager to receive events from AudioService), including lazy initialization of the listener list and stub to minimize memory usage The utility class is used to refactor the management of the following listeners: Spatializer.OnSpatializerStateChangedListener Spatializer.OnHeadTrackingModeChangedListener AudioManager.OnModeChangedListener AudioManager.OnCommunicationDeviceChangedListener Bug: 206040617 Test: atest AudioModeListenerTest AudioCommunicationDeviceTest \ SpatializerTest Change-Id: Ia37f1b19603282e0f14e6e5afc1226891e3c1d78