Implement asynchronous interface/plumbing for GetDefaultPrintSettings.

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 b57e8ebf34e06bbb578130683c0e2286b3242348..6da6ad095583ea219cb8a6431ded7f9876e0c632 100644
--- a/ppapi/proxy/ppapi_messages.h
+++ b/ppapi/proxy/ppapi_messages.h
@@ -415,6 +415,11 @@ IPC_MESSAGE_ROUTED2(PpapiMsg_PPBGraphics3D_SwapBuffersACK,
 IPC_MESSAGE_ROUTED2(PpapiMsg_PPBInstance_MouseLockComplete,
                     PP_Instance /* instance */,
                     int32_t /* result */)
+IPC_MESSAGE_ROUTED4(PpapiMsg_PPBInstance_GetDefaultPrintSettingsComplete,
+                    int32 /* routing_id */,
+                    PP_Instance /* instance */,
+                    PP_PrintSettings_Dev /* settings */,
+                    int32_t /* result */)
 
 // PPP_Class.
 IPC_SYNC_MESSAGE_ROUTED3_2(PpapiMsg_PPPClass_HasProperty,
@@ -964,10 +969,9 @@ IPC_MESSAGE_ROUTED1(PpapiHostMsg_PPBInstance_LockMouse,
                     PP_Instance /* instance */)
 IPC_MESSAGE_ROUTED1(PpapiHostMsg_PPBInstance_UnlockMouse,
                     PP_Instance /* instance */)
-IPC_SYNC_MESSAGE_ROUTED1_2(PpapiHostMsg_PPBPInstance_GetDefaultPrintSettings,
-                           PP_Instance /* instance */,
-                           PP_PrintSettings_Dev /* settings */,
-                           bool /* result */)
+IPC_MESSAGE_ROUTED2(PpapiHostMsg_PPBPInstance_GetDefaultPrintSettings,
+                    int32 /* routing_id */,
+                    PP_Instance /* instance */)
 IPC_SYNC_MESSAGE_ROUTED2_1(PpapiHostMsg_PPBInstance_ResolveRelativeToDocument,
                            PP_Instance /* instance */,
                            ppapi::proxy::SerializedVar /* relative */,