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 bc0a60d39f9e298ab5029ace711a9ec6966003ed..77ac819808fab1701463c613903ead4e152e816d 100644
--- a/ppapi/proxy/ppapi_messages.h
+++ b/ppapi/proxy/ppapi_messages.h
@@ -1583,9 +1583,6 @@ 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 */,
@@ -1596,6 +1593,17 @@ 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,