Add the pdf plugin's source in src\pdf.

pdf/pdfium/pdfium_mem_buffer_file_write.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 PDF_PDFIUM_PDFIUM_MEM_BUFFER_FILE_WRITE_
+#define PDF_PDFIUM_PDFIUM_MEM_BUFFER_FILE_WRITE_
+
+#include <string>
+
+#include "third_party/pdfium/fpdfsdk/include/fpdfsave.h"
+
+namespace chrome_pdf {
+
+// Implementation of FPDF_FILEWRITE into a memory buffer.
+class PDFiumMemBufferFileWrite : public FPDF_FILEWRITE {
+ public:
+  PDFiumMemBufferFileWrite();
+  ~PDFiumMemBufferFileWrite();
+
+  const std::basic_string<unsigned char>& buffer() { return buffer_; }
+  size_t size() { return buffer_.size(); }
+
+ private:
+  int DoWriteBlock(const void* data, unsigned long size);
+  static int WriteBlockImpl(FPDF_FILEWRITE* this_file_write, const void* data,
+                            unsigned long size);
+
+  std::basic_string<unsigned char> buffer_;
+};
+
+}  // namespace chrome_pdf
+
+#endif  // PDF_PDFIUM_PDFIUM_MEM_BUFFER_FILE_WRITE_
+