Revert 251207 "Use gpu::Mailbox instead of std:string in IPCs"

trunk/src/content/browser/browser_plugin/browser_plugin_guest.h

Index: trunk/src/content/browser/browser_plugin/browser_plugin_guest.h
===================================================================
--- trunk/src/content/browser/browser_plugin/browser_plugin_guest.h	(revision 251280)
+++ trunk/src/content/browser/browser_plugin/browser_plugin_guest.h	(working copy)
@@ -67,10 +67,6 @@
 class Range;
 }
 
-namespace gpu {
-struct Mailbox;
-}
-
 namespace content {
 
 class BrowserPluginHostFactory;
@@ -290,7 +286,7 @@
   // BrowserPluginGuest is already destroyed.
   static void AcknowledgeBufferPresent(int route_id,
                                        int gpu_host_id,
-                                       const gpu::Mailbox& mailbox,
+                                       const std::string& mailbox_name,
                                        uint32 sync_point);
 
   // Returns whether BrowserPluginGuest is interested in receiving the given