Use gpu::Mailbox in IPCs instead of std::string

content/common/browser_plugin/browser_plugin_messages.h

Index: content/common/browser_plugin/browser_plugin_messages.h
diff --git a/content/common/browser_plugin/browser_plugin_messages.h b/content/common/browser_plugin/browser_plugin_messages.h
index 66b2c8f140d67be4ed82dbf70f62c2a9c63d6ad3..b35f99ec9ca47cf0da0c36f542a01d4099f76493 100644
--- a/content/common/browser_plugin/browser_plugin_messages.h
+++ b/content/common/browser_plugin/browser_plugin_messages.h
@@ -14,6 +14,7 @@
 #include "content/common/content_export.h"
 #include "content/common/content_param_traits.h"
 #include "content/public/common/common_param_traits.h"
+#include "gpu/command_buffer/common/mailbox.h"
 #include "ipc/ipc_channel_handle.h"
 #include "ipc/ipc_message_macros.h"
 #include "ipc/ipc_message_utils.h"
@@ -207,7 +208,7 @@ IPC_MESSAGE_ROUTED5(BrowserPluginHostMsg_BuffersSwappedACK,
                     int /* instance_id */,
                     int /* route_id */,
                     int /* gpu_host_id */,
-                    std::string /* mailbox_name */,
+                    gpu::Mailbox /* mailbox_name */,
                     uint32 /* sync_point */)
 
 // When a BrowserPlugin has been removed from the embedder's DOM, it informs
@@ -384,7 +385,7 @@ IPC_MESSAGE_CONTROL2(BrowserPluginMsg_UpdatedName,
 IPC_MESSAGE_CONTROL5(BrowserPluginMsg_BuffersSwapped,
                      int /* instance_id */,
                      gfx::Size /* size */,
-                     std::string /* mailbox_name */,
+                     gpu::Mailbox /* mailbox_name */,
                      int /* route_id */,
                      int /* gpu_host_id */)