Convert more interfaces to the new thunk system.

ppapi/proxy/plugin_resource_tracker.h

Index: ppapi/proxy/plugin_resource_tracker.h
===================================================================
--- ppapi/proxy/plugin_resource_tracker.h	(revision 87260)
+++ ppapi/proxy/plugin_resource_tracker.h	(working copy)
@@ -8,6 +8,7 @@
 #include <map>
 #include <utility>
 
+#include "base/compiler_specific.h"
 #include "base/memory/linked_ptr.h"
 #include "ppapi/c/pp_completion_callback.h"
 #include "ppapi/c/pp_instance.h"
@@ -56,10 +57,11 @@
 
   // TrackerBase.
   virtual ::ppapi::ResourceObjectBase* GetResourceAPI(
-      PP_Resource res);
+      PP_Resource res) OVERRIDE;
   virtual ::ppapi::FunctionGroupBase* GetFunctionAPI(
       PP_Instance inst,
-      pp::proxy::InterfaceID id);
+      pp::proxy::InterfaceID id) OVERRIDE;
+  virtual PP_Instance GetInstanceForResource(PP_Resource resource) OVERRIDE;
 
  private:
   friend struct DefaultSingletonTraits<PluginResourceTracker>;