Update {virtual,override} to follow C++11 style in ppapi.

ppapi/proxy/plugin_array_buffer_var.h

 // Copyright (c) 2012 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_PROXY_PLUGIN_ARRAY_BUFFER_VAR_H_
 #define PPAPI_PROXY_PLUGIN_ARRAY_BUFFER_VAR_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/shared_memory.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/c/pp_stdint.h"
 #include "ppapi/shared_impl/var.h"
 
 namespace ppapi {
 
 // Represents a plugin-side ArrayBufferVar. In the plugin process, it's
 // owned as a vector.
 class PluginArrayBufferVar : public ArrayBufferVar {
  public:
   explicit PluginArrayBufferVar(uint32 size_in_bytes);
   PluginArrayBufferVar(uint32 size_in_bytes,
                        base::SharedMemoryHandle plugin_handle);
-  virtual ~PluginArrayBufferVar();
+  ~PluginArrayBufferVar() override;
 
   // ArrayBufferVar implementation.
-  virtual void* Map() override;
-  virtual void Unmap() override;
-  virtual uint32 ByteLength() override;
-  virtual bool CopyToNewShmem(
+  void* Map() override;
+  void Unmap() override;
+  uint32 ByteLength() override;
+  bool CopyToNewShmem(
       PP_Instance instance,
       int* host_handle,
       base::SharedMemoryHandle* plugin_handle) override;
 
  private:
   // Non-shared memory
   std::vector<uint8> buffer_;
 
   // Shared memory
   base::SharedMemoryHandle plugin_handle_;
   scoped_ptr<base::SharedMemory> shmem_;
   uint32 size_in_bytes_;
 
   DISALLOW_COPY_AND_ASSIGN(PluginArrayBufferVar);
 };
 
 }  // namespace ppapi
 
 #endif  // PPAPI_PROXY_PLUGIN_ARRAY_BUFFER_VAR_H_