Remove unused code for managing physical audio devices.

This was only used in B2G/Gonk and can go.

hal/HalTypes.h

@@ -33,26 +33,6 @@ enum ShutdownMode {
   eHalShutdownMode_Count    = 3
 };
 
-class SwitchEvent;
-
-enum SwitchDevice {
-  SWITCH_DEVICE_UNKNOWN = -1,
-  SWITCH_HEADPHONES,
-  SWITCH_USB,
-  NUM_SWITCH_DEVICE
-};
-
-enum SwitchState {
-  SWITCH_STATE_UNKNOWN = -1,
-  SWITCH_STATE_ON,
-  SWITCH_STATE_OFF,
-  SWITCH_STATE_HEADSET,          // Headphone with microphone
-  SWITCH_STATE_HEADPHONE,        // without microphone
-  NUM_SWITCH_STATE
-};
-
-typedef Observer<SwitchEvent> SwitchObserver;
-
 // Note that we rely on the order of this enum's entries.  Higher priorities
 // should have larger int values.
 enum ProcessPriority {
@@ -141,28 +121,6 @@ struct ParamTraits<mozilla::hal::WakeLockControl>
              mozilla::hal::NUM_WAKE_LOCK>
 {};
 
-/**
- * Serializer for SwitchState
- */
-template <>
-struct ParamTraits<mozilla::hal::SwitchState>:
-  public ContiguousEnumSerializer<
-           mozilla::hal::SwitchState,
-           mozilla::hal::SWITCH_STATE_UNKNOWN,
-           mozilla::hal::NUM_SWITCH_STATE> {
-};
-
-/**
- * Serializer for SwitchDevice
- */
-template <>
-struct ParamTraits<mozilla::hal::SwitchDevice>:
-  public ContiguousEnumSerializer<
-           mozilla::hal::SwitchDevice,
-           mozilla::hal::SWITCH_DEVICE_UNKNOWN,
-           mozilla::hal::NUM_SWITCH_DEVICE> {
-};
-
 template <>
 struct ParamTraits<mozilla::hal::ProcessPriority>:
   public ContiguousEnumSerializer<