Use the WebKit default fonts when specifying generic font families.

ppapi/proxy/ppapi_messages.h

Index: ppapi/proxy/ppapi_messages.h
===================================================================
--- ppapi/proxy/ppapi_messages.h	(revision 86427)
+++ ppapi/proxy/ppapi_messages.h	(working copy)
@@ -29,6 +29,7 @@
 #include "ppapi/proxy/ppapi_param_traits.h"
 #include "ppapi/proxy/serialized_flash_menu.h"
 #include "ppapi/proxy/serialized_structs.h"
+#include "ppapi/shared_impl/ppapi_preferences.h"
 
 #define IPC_MESSAGE_START PpapiMsgStart
 
@@ -47,6 +48,15 @@
   IPC_STRUCT_TRAITS_MEMBER(size)
 IPC_STRUCT_TRAITS_END()
 
+IPC_STRUCT_TRAITS_BEGIN(::ppapi::Preferences)
+  IPC_STRUCT_TRAITS_MEMBER(standard_font_family)
+  IPC_STRUCT_TRAITS_MEMBER(fixed_font_family)
+  IPC_STRUCT_TRAITS_MEMBER(serif_font_family)
+  IPC_STRUCT_TRAITS_MEMBER(sans_serif_font_family)
+  IPC_STRUCT_TRAITS_MEMBER(default_font_size)
+  IPC_STRUCT_TRAITS_MEMBER(default_fixed_font_size)
+IPC_STRUCT_TRAITS_END()
+
 // These are from the browser to the plugin.
 // Loads the given plugin.
 IPC_MESSAGE_CONTROL1(PpapiMsg_LoadPlugin, FilePath /* path */)
@@ -75,6 +85,10 @@
                             PP_Instance /* instance */,
                             bool /* usable */)
 
+// Passes the WebKit preferences to the plugin.
+IPC_MESSAGE_CONTROL1(PpapiMsg_SetPreferences,
+                     ::ppapi::Preferences)
+
 // Sent in both directions to see if the other side supports the given
 // interface.
 IPC_SYNC_MESSAGE_CONTROL1_1(PpapiMsg_SupportsInterface,