Add the "virtual" keyword on method overrides that are missing it.

webkit/glue/plugins/pepper_buffer.cc

Index: webkit/glue/plugins/pepper_buffer.cc
diff --git a/webkit/glue/plugins/pepper_buffer.cc b/webkit/glue/plugins/pepper_buffer.cc
index b17370e16f138398a3f7b32deaf9bf099c45b57b..fc3c34d3b887c64be1544e20da7a68cb241784b3 100644
--- a/webkit/glue/plugins/pepper_buffer.cc
+++ b/webkit/glue/plugins/pepper_buffer.cc
@@ -81,6 +81,8 @@ const PPB_Buffer_Dev* Buffer::GetInterface() {
   return &ppb_buffer;
 }
 
+Buffer* Buffer::AsBuffer() { return this; }
+
 bool Buffer::Init(uint32_t size) {
   if (size == 0)
     return false;