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

ppapi/proxy/plugin_array_buffer_var.h

Index: ppapi/proxy/plugin_array_buffer_var.h
diff --git a/ppapi/proxy/plugin_array_buffer_var.h b/ppapi/proxy/plugin_array_buffer_var.h
index efe90403286c944e3f7c91f6f1a241777c65eeb8..ee9b930645790a6dff51bde4e7a6c59bf4309555 100644
--- a/ppapi/proxy/plugin_array_buffer_var.h
+++ b/ppapi/proxy/plugin_array_buffer_var.h
@@ -23,13 +23,13 @@ class PluginArrayBufferVar : public ArrayBufferVar {
   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;