Proxy PPB_ArrayBuffer_Dev, make them work over Messaging

ppapi/native_client/src/shared/ppapi_proxy/array_buffer_proxy_var.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 NATIVE_CLIENT_SRC_SHARED_PPAPI_PROXY_ARRAY_BUFFER_PROXY_VAR_H_
+#define NATIVE_CLIENT_SRC_SHARED_PPAPI_PROXY_ARRAY_BUFFER_PROXY_VAR_H_
+
+#include "native_client/src/include/nacl_memory.h"
+#include "native_client/src/shared/ppapi_proxy/proxy_var.h"
+
+#include <vector>
+
+namespace ppapi_proxy {
+
+// Subclass of ProxyVar that handles ArrayBuffer objects.
+class ArrayBufferProxyVar : public ProxyVar {
+ public:
+  explicit ArrayBufferProxyVar(uint32_t size_in_bytes)
+      : ProxyVar(PP_VARTYPE_ARRAY_BUFFER), buffer_(size_in_bytes, 0) {}
+
+  void* buffer() { return buffer_.empty() ? NULL : &buffer_[0]; }
+  uint32_t buffer_length() const { return buffer_.size(); }
+
+  // Convenience function to do type checking and down-casting. This returns a
+  // scoped_refptr<>, so you don't have to down-cast the raw pointer.
+  static scoped_refptr<ArrayBufferProxyVar> CastFromProxyVar(
+      SharedProxyVar proxy_var) {
+    if (proxy_var == NULL ||
+        proxy_var->pp_var_type() != PP_VARTYPE_ARRAY_BUFFER) {
+      scoped_refptr<ArrayBufferProxyVar> null_ptr;
+      return null_ptr;
+    }
+    return scoped_refptr<ArrayBufferProxyVar>(
+        static_cast<ArrayBufferProxyVar*>(proxy_var.get()));
+  }
+
+ private:
+  std::vector<uint8_t> buffer_;
+};
+
+typedef scoped_refptr<ArrayBufferProxyVar> SharedArrayBufferProxyVar;
+
+}  // namespace ppapi_proxy
+
+#endif  // NATIVE_CLIENT_SRC_SHARED_PPAPI_PROXY_ARRAY_BUFFER_PROXY_VAR_H_