Make (and verify) public/ files compile under C.

samples/pdfium_test.cc

 // 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.
 
 #include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include <list>
@@ skipping 395 matching lines @@
 }
 
 int Get_Block(void* param, unsigned long pos, unsigned char* pBuf,
               unsigned long size) {
   TestLoader* pLoader = (TestLoader*) param;
   if (pos + size < pos || pos + size > pLoader->m_Len) return 0;
   memcpy(pBuf, pLoader->m_pBuf + pos, size);
   return 1;
 }
 
-bool Is_Data_Avail(FX_FILEAVAIL* pThis, size_t offset, size_t size) {
+FPDF_BOOL Is_Data_Avail(FX_FILEAVAIL* pThis, size_t offset, size_t size) {
   return true;
 }
 
 void Add_Segment(FX_DOWNLOADHINTS* pThis, size_t offset, size_t size) {
 }
 
 void RenderPdf(const std::string& name, const char* pBuf, size_t len,
                const Options& options) {
   fprintf(stderr, "Rendering PDF file %s.\n", name.c_str());
 
@@ skipping 186 matching lines @@
     RenderPdf(filename, file_contents, file_length, options);
     free(file_contents);
   }
 
   FPDF_DestroyLibrary();
   v8::V8::ShutdownPlatform();
   delete platform;
 
   return 0;
 }