Add support for passing an arbitrary parameter to an IPC message handler. The motivation is for Web…

chrome/browser/renderer_host/pepper/pepper_flash_drm_host.cc

Index: chrome/browser/renderer_host/pepper/pepper_flash_drm_host.cc
===================================================================
--- chrome/browser/renderer_host/pepper/pepper_flash_drm_host.cc	(revision 270145)
+++ chrome/browser/renderer_host/pepper/pepper_flash_drm_host.cc	(working copy)
@@ -136,14 +136,14 @@
 int32_t PepperFlashDRMHost::OnResourceMessageReceived(
     const IPC::Message& msg,
     ppapi::host::HostMessageContext* context) {
-  IPC_BEGIN_MESSAGE_MAP(PepperFlashDRMHost, msg)
-  PPAPI_DISPATCH_HOST_RESOURCE_CALL_0(PpapiHostMsg_FlashDRM_GetDeviceID,
-                                      OnHostMsgGetDeviceID)
-  PPAPI_DISPATCH_HOST_RESOURCE_CALL_0(PpapiHostMsg_FlashDRM_GetHmonitor,
-                                      OnHostMsgGetHmonitor)
-  PPAPI_DISPATCH_HOST_RESOURCE_CALL_0(PpapiHostMsg_FlashDRM_MonitorIsExternal,
-                                      OnHostMsgMonitorIsExternal)
-  IPC_END_MESSAGE_MAP()
+  PPAPI_BEGIN_MESSAGE_MAP(PepperFlashDRMHost, msg)
+    PPAPI_DISPATCH_HOST_RESOURCE_CALL_0(PpapiHostMsg_FlashDRM_GetDeviceID,
+                                        OnHostMsgGetDeviceID)
+    PPAPI_DISPATCH_HOST_RESOURCE_CALL_0(PpapiHostMsg_FlashDRM_GetHmonitor,
+                                        OnHostMsgGetHmonitor)
+    PPAPI_DISPATCH_HOST_RESOURCE_CALL_0(PpapiHostMsg_FlashDRM_MonitorIsExternal,
+                                        OnHostMsgMonitorIsExternal)
+  PPAPI_END_MESSAGE_MAP()
   return PP_ERROR_FAILED;
 }