Add virtual destructors for the Pepper API thunks.

ppapi/thunk/ppb_context_3d_api.h

 // Copyright (c) 2011 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_THUNK_PPB_CONTEXT_3D_API_H_
 #define PPAPI_THUNK_PPB_CONTEXT_3D_API_H_
 
 #include "ppapi/c/dev/ppb_context_3d_dev.h"
 #include "ppapi/c/dev/ppb_context_3d_trusted_dev.h"
 #include "ppapi/c/dev/ppb_gles_chromium_texture_mapping_dev.h"
 
 namespace ppapi {
 namespace thunk {
 
 class PPB_Context3D_API {
  public:
+  virtual ~PPB_Context3D_API() {}
+
   // Context3D.
   virtual int32_t GetAttrib(int32_t attribute, int32_t* value) = 0;
   virtual int32_t BindSurfaces(PP_Resource draw, PP_Resource read) = 0;
   virtual int32_t GetBoundSurfaces(PP_Resource* draw, PP_Resource* read) = 0;
 
   // Context3DTrusted.
   virtual PP_Bool InitializeTrusted(int32_t size) = 0;
   virtual PP_Bool GetRingBuffer(int* shm_handle,
                                 uint32_t* shm_size) = 0;
   virtual PP_Context3DTrustedState GetState() = 0;
@@ skipping 17 matching lines @@
                                          GLenum format,
                                          GLenum type,
                                          GLenum access) = 0;
   virtual void UnmapTexSubImage2DCHROMIUM(const void* mem) = 0;
 };
 
 }  // namespace thunk
 }  // namespace ppapi
 
 #endif  // PPAPI_THUNK_PPB_CONTEXT_3D_API_H_