Include what you use in ppb_surface_3d_dev.h.

ppapi/c/dev/ppb_surface_3d_dev.h

 /* Copyright (c) 2010 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef PPAPI_C_DEV_PPB_SURFACE_3D_DEV_H_
 #define PPAPI_C_DEV_PPB_SURFACE_3D_DEV_H_
 
 #include "ppapi/c/dev/pp_graphics_3d_dev.h"
 #include "ppapi/c/pp_bool.h"
+#include "ppapi/c/pp_completion_callback.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/c/pp_resource.h"
 
 #define PPB_SURFACE_3D_DEV_INTERFACE "PPB_Surface3D(Dev);0.1"
 
 struct PPB_Surface3D_Dev {
   // Creates a render surface and returns a handle to it.
   // Any PPB_Context3D_Dev created with a compatible PP_Config3D_Dev
   // can be used to render into this surface. The returned surface is
   // off-screen to start with. It must be attached to a plugin instance
@@ skipping 81 matching lines @@
   // plugin's current state is actually on the screen, this function provides a
   // way to rate limit animations. By waiting until the image is on the screen
   // before painting the next frame, you can ensure you're not generating
   // updates faster than the screen can be updated.
   //
   int32_t (*SwapBuffers)(PP_Resource surface,
                          struct PP_CompletionCallback callback);
 };
 
 #endif  // PPAPI_C_DEV_PPB_SURFACE_3D_DEV_H_