Remove the proxy callback tracker.

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 a6505778bad40cfba65bdab39049e4e41be4fe7d..df91d509f5466e02a2b7a2cb9ee46d1590040e1d 100644
--- a/ppapi/proxy/ppapi_messages.h
+++ b/ppapi/proxy/ppapi_messages.h
@@ -193,10 +193,6 @@ IPC_SYNC_MESSAGE_CONTROL1_1(PpapiMsg_SupportsInterface,
                             std::string /* interface_name */,
                             bool /* result */)
 
-IPC_MESSAGE_CONTROL2(PpapiMsg_ExecuteCallback,
-                     uint32 /* serialized_callback */,
-                     int32 /* param */)
-
 // Broker Process.
 
 IPC_SYNC_MESSAGE_CONTROL2_1(PpapiMsg_ConnectToPlugin,
@@ -234,6 +230,13 @@ IPC_MESSAGE_ROUTED3(
     int32_t /* result_code (will be != PP_OK on failure */,
     std::vector<ppapi::PPB_FileRef_CreateInfo> /* chosen_files */)
 
+// PPB_FileRef.
+IPC_MESSAGE_ROUTED3(
+    PpapiMsg_PPBFileRef_CallbackComplete,
+    ppapi::HostResource /* resource */,
+    int /* callback_id */,
+    int32_t /* result */)
+
 // PPB_FileSystem.
 IPC_MESSAGE_ROUTED2(
     PpapiMsg_PPBFileSystem_OpenComplete,
@@ -297,6 +300,11 @@ IPC_MESSAGE_ROUTED2(PpapiMsg_PPBGraphics3D_SwapBuffersACK,
                     ppapi::HostResource /* graphics_3d */,
                     int32_t /* pp_error */)
 
+// PPB_Instance.
+IPC_MESSAGE_ROUTED2(PpapiMsg_PPBInstance_MouseLockComplete,
+                    PP_Instance /* instance */,
+                    int32_t /* result */)
+
 // PPB_Surface3D.
 IPC_MESSAGE_ROUTED2(PpapiMsg_PPBSurface3D_SwapBuffersACK,
                     ppapi::HostResource /* surface_3d */,
@@ -412,6 +420,9 @@ IPC_MESSAGE_ROUTED3(PpapiMsg_PPBURLLoader_ReadResponseBody_Ack,
                     ppapi::HostResource /* loader */,
                     int32 /* result */,
                     std::string /* data */)
+IPC_MESSAGE_ROUTED2(PpapiMsg_PPBURLLoader_CallbackComplete,
+                    ppapi::HostResource /* loader */,
+                    int32_t /* result */)
 
 // PPP_VideoCapture_Dev
 IPC_MESSAGE_ROUTED3(
@@ -575,7 +586,6 @@ IPC_SYNC_MESSAGE_ROUTED3_1(PpapiHostMsg_PPBFileChooser_Create,
 IPC_MESSAGE_ROUTED1(PpapiHostMsg_PPBFileChooser_Show,
                     ppapi::HostResource /* file_chooser */)
 
-
 // PPB_FileRef.
 IPC_SYNC_MESSAGE_ROUTED2_1(PpapiHostMsg_PPBFileRef_Create,
                            ppapi::HostResource /* file_system */,
@@ -587,19 +597,19 @@ IPC_SYNC_MESSAGE_ROUTED1_1(PpapiHostMsg_PPBFileRef_GetParent,
 IPC_MESSAGE_ROUTED3(PpapiHostMsg_PPBFileRef_MakeDirectory,
                     ppapi::HostResource /* file_ref */,
                     PP_Bool /* make_ancestors */,
-                    uint32_t /* serialized_callback */)
+                    int /* callback_id */)
 IPC_MESSAGE_ROUTED4(PpapiHostMsg_PPBFileRef_Touch,
                     ppapi::HostResource /* file_ref */,
                     PP_Time /* last_access */,
                     PP_Time /* last_modified */,
-                    uint32_t /* serialized_callback */)
+                    int /* callback_id */)
 IPC_MESSAGE_ROUTED2(PpapiHostMsg_PPBFileRef_Delete,
                     ppapi::HostResource /* file_ref */,
-                    uint32_t /* serialized_callback */)
+                    int /* callback_id */)
 IPC_MESSAGE_ROUTED3(PpapiHostMsg_PPBFileRef_Rename,
                     ppapi::HostResource /* file_ref */,
                     ppapi::HostResource /* new_file_ref */,
-                    uint32_t /* serialized_callback */)
+                    int /* callback_id */)
 
 // PPB_FileSystem.
 IPC_SYNC_MESSAGE_ROUTED2_1(PpapiHostMsg_PPBFileSystem_Create,
@@ -889,9 +899,8 @@ IPC_MESSAGE_ROUTED2(PpapiHostMsg_PPBInstance_ClearInputEvents,
 IPC_MESSAGE_ROUTED2(PpapiHostMsg_PPBInstance_PostMessage,
                     PP_Instance /* instance */,
                     ppapi::proxy::SerializedVar /* message */)
-IPC_MESSAGE_ROUTED2(PpapiHostMsg_PPBInstance_LockMouse,
-                    PP_Instance /* instance */,
-                    uint32_t /* serialized_callback */)
+IPC_MESSAGE_ROUTED1(PpapiHostMsg_PPBInstance_LockMouse,
+                    PP_Instance /* instance */)
 IPC_MESSAGE_ROUTED1(PpapiHostMsg_PPBInstance_UnlockMouse,
                     PP_Instance /* instance */)
 IPC_SYNC_MESSAGE_ROUTED2_1(PpapiHostMsg_PPBInstance_ResolveRelativeToDocument,
@@ -960,13 +969,11 @@ IPC_MESSAGE_ROUTED1(PpapiHostMsg_PPBTextInput_CancelCompositionText,
 IPC_SYNC_MESSAGE_ROUTED1_1(PpapiHostMsg_PPBURLLoader_Create,
                            PP_Instance /* instance */,
                            ppapi::HostResource /* result */)
-IPC_MESSAGE_ROUTED3(PpapiHostMsg_PPBURLLoader_Open,
+IPC_MESSAGE_ROUTED2(PpapiHostMsg_PPBURLLoader_Open,
                     ppapi::HostResource /* loader */,
-                    ppapi::PPB_URLRequestInfo_Data /* request_data */,
-                    uint32_t /* serialized_callback */)
-IPC_MESSAGE_ROUTED2(PpapiHostMsg_PPBURLLoader_FollowRedirect,
-                    ppapi::HostResource /* loader */,
-                    uint32_t /* serialized_callback */)
+                    ppapi::PPB_URLRequestInfo_Data /* request_data */)
+IPC_MESSAGE_ROUTED1(PpapiHostMsg_PPBURLLoader_FollowRedirect,
+                    ppapi::HostResource /* loader */)
 IPC_SYNC_MESSAGE_ROUTED1_1(
     PpapiHostMsg_PPBURLLoader_GetResponseInfo,
     ppapi::HostResource /* loader */,
@@ -974,9 +981,8 @@ IPC_SYNC_MESSAGE_ROUTED1_1(
 IPC_MESSAGE_ROUTED2(PpapiHostMsg_PPBURLLoader_ReadResponseBody,
                     ppapi::HostResource /* loader */,
                     int32_t /* bytes_to_read */)
-IPC_MESSAGE_ROUTED2(PpapiHostMsg_PPBURLLoader_FinishStreamingToFile,
-                    ppapi::HostResource /* loader */,
-                    uint32_t /* serialized_callback */)
+IPC_MESSAGE_ROUTED1(PpapiHostMsg_PPBURLLoader_FinishStreamingToFile,
+                    ppapi::HostResource /* loader */)
 IPC_MESSAGE_ROUTED1(PpapiHostMsg_PPBURLLoader_Close,
                     ppapi::HostResource /* loader */)
 IPC_MESSAGE_ROUTED1(PpapiHostMsg_PPBURLLoader_GrantUniversalAccess,