Introduce PPB_AudioInput_Dev v0.3 and refactor the device enumeration code:

ppapi/proxy/ppapi_messages.h

Index: ppapi/proxy/ppapi_messages.h
diff --git a/ppapi/proxy/ppapi_messages.h b/ppapi/proxy/ppapi_messages.h
index 1c8a3def8bacdf46a91dbe3f65a65185943c2a99..a0706fa82ee0745548048749b987be89d0610ac4 100644
--- a/ppapi/proxy/ppapi_messages.h
+++ b/ppapi/proxy/ppapi_messages.h
@@ -1682,9 +1682,6 @@ IPC_MESSAGE_CONTROL4(PpapiPluginMsg_WebSocket_ClosedReply,
 
 // Audio input.
 IPC_MESSAGE_CONTROL0(PpapiHostMsg_AudioInput_Create)
-IPC_MESSAGE_CONTROL0(PpapiHostMsg_AudioInput_EnumerateDevices)
-IPC_MESSAGE_CONTROL1(PpapiPluginMsg_AudioInput_EnumerateDevicesReply,
-                     std::vector<ppapi::DeviceRefData> /* devices */)
 IPC_MESSAGE_CONTROL3(PpapiHostMsg_AudioInput_Open,
                      std::string /* device_id */,
                      PP_AudioSampleRate /* sample_rate */,
@@ -1695,6 +1692,17 @@ IPC_MESSAGE_CONTROL0(PpapiPluginMsg_AudioInput_OpenReply)
 IPC_MESSAGE_CONTROL1(PpapiHostMsg_AudioInput_StartOrStop, bool /* capture */)
 IPC_MESSAGE_CONTROL0(PpapiHostMsg_AudioInput_Close)
 
+// Device enumeration messages used by audio input and video capture.
+IPC_MESSAGE_CONTROL0(PpapiHostMsg_DeviceEnumeration_EnumerateDevices)
+IPC_MESSAGE_CONTROL1(PpapiPluginMsg_DeviceEnumeration_EnumerateDevicesReply,
+                     std::vector<ppapi::DeviceRefData> /* devices */)
+IPC_MESSAGE_CONTROL1(PpapiHostMsg_DeviceEnumeration_MonitorDeviceChange,
+                     uint32_t /* callback_id */)
+IPC_MESSAGE_CONTROL0(PpapiHostMsg_DeviceEnumeration_StopMonitoringDeviceChange)
+IPC_MESSAGE_CONTROL2(PpapiPluginMsg_DeviceEnumeration_NotifyDeviceChange,
+                     uint32_t /* callback_id */,
+                     std::vector<ppapi::DeviceRefData> /* devices */)
+
 // Flash clipboard.
 IPC_MESSAGE_CONTROL0(PpapiHostMsg_FlashClipboard_Create)
 IPC_MESSAGE_CONTROL1(PpapiHostMsg_FlashClipboard_RegisterCustomFormat,