text: // 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.
  
  #include <map>
  #include <string>
  
  #include "net/base/mime_util.h"
  #include "net/base/platform_mime_util.h"
  
  #include "base/hash_tables.h"
  #include "base/lazy_instance.h"
  #include "base/logging.h"
  #include "base/string_split.h"
  #include "base/string_util.h"
  #include "base/utf_string_conversions.h"
  
  using std::string;
  
  namespace net {
  
  // Singleton utility class for mime types.
  class MimeUtil : public PlatformMimeUtil {
   public:
    bool GetMimeTypeFromExtension(const FilePath::StringType& ext,
                                  std::string* mime_type) const;
  
    bool GetMimeTypeFromFile(const FilePath& file_path,
                             std::string* mime_type) const;
  
    bool IsSupportedImageMimeType(const char* mime_type) const;
    bool IsSupportedMediaMimeType(const char* mime_type) const;
    bool IsSupportedNonImageMimeType(const char* mime_type) const;
    bool IsSupportedJavascriptMimeType(const char* mime_type) const;
  
    bool IsViewSourceMimeType(const char* mime_type) const;
  
    bool IsSupportedMimeType(const std::string& mime_type) const;
  
    bool MatchesMimeType(const std::string &mime_type_pattern,
                         const std::string &mime_type) const;
  
    bool AreSupportedMediaCodecs(const std::vector<std::string>& codecs) const;
  
    void ParseCodecString(const std::string& codecs,
                          std::vector<std::string>* codecs_out,
                          bool strip);
  
    bool IsStrictMediaMimeType(const std::string& mime_type) const;
    bool IsSupportedStrictMediaMimeType(const std::string& mime_type,
        const std::vector<std::string>& codecs) const;
  
   private:
    friend struct base::DefaultLazyInstanceTraits<MimeUtil>;
    MimeUtil() {
      InitializeMimeTypeMaps();
    }
  
    // For faster lookup, keep hash sets.
    void InitializeMimeTypeMaps();
  
    typedef base::hash_set<std::string> MimeMappings;
    MimeMappings image_map_;
    MimeMappings media_map_;
    MimeMappings non_image_map_;
    MimeMappings javascript_map_;
    MimeMappings view_source_map_;
    MimeMappings codecs_map_;
  
    typedef std::map<std::string, base::hash_set<std::string> > StrictMappings;
    StrictMappings strict_format_map_;
  };  // class MimeUtil
  
  static base::LazyInstance<MimeUtil> g_mime_util(base::LINKER_INITIALIZED);
  
  struct MimeInfo {
    const char* mime_type;
    const char* extensions;  // comma separated list
  };
  
  static const MimeInfo primary_mappings[] = {
    { "text/html", "html,htm" },
    { "text/css", "css" },
    { "text/xml", "xml" },
    { "image/gif", "gif" },
    { "image/jpeg", "jpeg,jpg" },
    { "image/webp", "webp" },
    { "image/png", "png" },
    { "video/mp4", "mp4,m4v" },
    { "audio/x-m4a", "m4a" },
    { "audio/mp3", "mp3" },
    { "video/ogg", "ogv,ogm" },
    { "audio/ogg", "ogg,oga" },
    { "video/webm", "webm" },
    { "audio/webm", "webm" },
    { "audio/wav", "wav" },
    { "application/xhtml+xml", "xhtml,xht" },
    { "application/x-chrome-extension", "crx" }
  };
  
  static const MimeInfo secondary_mappings[] = {
    { "application/octet-stream", "exe,com,bin" },
    { "application/gzip", "gz" },
    { "application/pdf", "pdf" },
    { "application/postscript", "ps,eps,ai" },
    { "application/x-javascript", "js" },
    { "image/bmp", "bmp" },
    { "image/x-icon", "ico" },
    { "image/jpeg", "jfif,pjpeg,pjp" },
    { "image/tiff", "tiff,tif" },
    { "image/x-xbitmap", "xbm" },
    { "image/svg+xml", "svg,svgz" },
    { "message/rfc822", "eml" },
    { "text/plain", "txt,text" },
    { "text/html", "shtml,ehtml" },
    { "application/rss+xml", "rss" },
    { "application/rdf+xml", "rdf" },
    { "text/xml", "xsl,xbl" },
    { "application/vnd.mozilla.xul+xml", "xul" },
    { "application/x-shockwave-flash", "swf,swl" }
  };
  
  static const char* FindMimeType(const MimeInfo* mappings,
                                  size_t mappings_len,
                                  const char* ext) {
    size_t ext_len = strlen(ext);
  
    for (size_t i = 0; i < mappings_len; ++i) {
      const char* extensions = mappings[i].extensions;
      for (;;) {
        size_t end_pos = strcspn(extensions, ",");
        if (end_pos == ext_len &&
            base::strncasecmp(extensions, ext, ext_len) == 0)
          return mappings[i].mime_type;
        extensions += end_pos;
        if (!*extensions)
          break;
        extensions += 1;  // skip over comma
      }
    }
    return NULL;
  }
  
  bool MimeUtil::GetMimeTypeFromExtension(const FilePath::StringType& ext,
                                          string* result) const {
    // Avoids crash when unable to handle a long file path. See crbug.com/48733.
    const unsigned kMaxFilePathSize = 65536;
    if (ext.length() > kMaxFilePathSize)
      return false;
  
    // We implement the same algorithm as Mozilla for mapping a file extension to
    // a mime type.  That is, we first check a hard-coded list (that cannot be
    // overridden), and then if not found there, we defer to the system registry.
    // Finally, we scan a secondary hard-coded list to catch types that we can
    // deduce but that we also want to allow the OS to override.
  
  #if defined(OS_WIN)
    string ext_narrow_str = WideToUTF8(ext);
  #elif defined(OS_POSIX)
    const string& ext_narrow_str = ext;
  #endif
    const char* mime_type;
  
    mime_type = FindMimeType(primary_mappings, arraysize(primary_mappings),
                             ext_narrow_str.c_str());
    if (mime_type) {
      *result = mime_type;
      return true;
    }
  
    if (GetPlatformMimeTypeFromExtension(ext, result))
      return true;
  
    mime_type = FindMimeType(secondary_mappings, arraysize(secondary_mappings),
                             ext_narrow_str.c_str());
    if (mime_type) {
      *result = mime_type;
      return true;
    }
  
    return false;
  }
  
  bool MimeUtil::GetMimeTypeFromFile(const FilePath& file_path,
                                     string* result) const {
    FilePath::StringType file_name_str = file_path.Extension();
    if (file_name_str.empty())
      return false;
    return GetMimeTypeFromExtension(file_name_str.substr(1), result);
  }
  
  // From WebKit's WebCore/platform/MIMETypeRegistry.cpp:
  
  static const char* const supported_image_types[] = {
    "image/jpeg",
    "image/pjpeg",
    "image/jpg",
    "image/webp",
    "image/png",
    "image/gif",
    "image/bmp",
    "image/x-icon",    // ico
    "image/x-xbitmap"  // xbm
  };
  
  // A list of media types: http://en.wikipedia.org/wiki/Internet_media_type
  // A comprehensive mime type list: http://plugindoc.mozdev.org/winmime.php
  static const char* const supported_media_types[] = {
    // Ogg.
    "video/ogg",
    "audio/ogg",
    "application/ogg",
    "video/webm",
    "audio/webm",
    "audio/wav",
    "audio/x-wav",
  
  #if defined (TOOLKIT_MEEGOTOUCH)
    /*_DEV2_H264_*/
    // MPEG-4.
    "video/mp4",
    "video/x-m4v",
    "audio/mp4",
    "audio/x-m4a",
  #endif
  
  #if defined(GOOGLE_CHROME_BUILD) || defined(USE_PROPRIETARY_CODECS)
    // MPEG-4.
    "video/mp4",
    "video/x-m4v",
    "audio/mp4",
    "audio/x-m4a",
  
    // MP3.
    "audio/mp3",
    "audio/x-mp3",
    "audio/mpeg",
  #endif
  };
  
  // List of supported codecs when passed in with <source type="...">.
  //
  // Refer to http://wiki.whatwg.org/wiki/Video_type_parameters#Browser_Support
  // for more information.
  static const char* const supported_media_codecs[] = {
  #if defined (TOOLKIT_MEEGOTOUCH)
    /*_DEV2_H264_*/
    "avc1", /*enable H264 and mp4a for HTML5*/
    "mp4a",
  #endif
  #if defined(GOOGLE_CHROME_BUILD) || defined(USE_PROPRIETARY_CODECS)
    "avc1",
    "mp4a",
  #endif
    "theora",
    "vorbis",
    "vp8",
    "1"  // PCM for WAV.
  };
  
  // Note: does not include javascript types list (see supported_javascript_types)
  static const char* const supported_non_image_types[] = {
    "text/cache-manifest",
    "text/html",
    "text/xml",
    "text/xsl",
    "text/plain",
    // Many users complained about css files served for
    // download instead of displaying in the browser:
    // http://code.google.com/p/chromium/issues/detail?id=7192
    // So, by including "text/css" into this list we choose Firefox
    // behavior - css files will be displayed:
    "text/css",
    "text/vnd.chromium.ftp-dir",
    "text/",
    "image/svg+xml",  // SVG is text-based XML, even though it has an image/ type
    "application/xml",
    "application/xhtml+xml",
    "application/rss+xml",
    "application/atom+xml",
    "application/json",
    "application/x-x509-user-cert",
    "multipart/x-mixed-replace"
    // Note: ADDING a new type here will probably render it AS HTML. This can
    // result in cross site scripting.
  };
  COMPILE_ASSERT(arraysize(supported_non_image_types) == 16,
                 supported_non_images_types_must_equal_16);
  
  //  Mozilla 1.8 and WinIE 7 both accept text/javascript and text/ecmascript.
  //  Mozilla 1.8 accepts application/javascript, application/ecmascript, and
  // application/x-javascript, but WinIE 7 doesn't.
  //  WinIE 7 accepts text/javascript1.1 - text/javascript1.3, text/jscript, and
  // text/livescript, but Mozilla 1.8 doesn't.
  //  Mozilla 1.8 allows leading and trailing whitespace, but WinIE 7 doesn't.
  //  Mozilla 1.8 and WinIE 7 both accept the empty string, but neither accept a
  // whitespace-only string.
  //  We want to accept all the values that either of these browsers accept, but
  // not other values.
  static const char* const supported_javascript_types[] = {
    "text/javascript",
    "text/ecmascript",
    "application/javascript",
    "application/ecmascript",
    "application/x-javascript",
    "text/javascript1.1",
    "text/javascript1.2",
    "text/javascript1.3",
    "text/jscript",
    "text/livescript"
  };
  
  static const char* const view_source_types[] = {
    "text/xml",
    "text/xsl",
    "application/xml",
    "application/rss+xml",
    "application/atom+xml",
    "image/svg+xml"
  };
  
  struct MediaFormatStrict {
    const char* mime_type;
    const char* codecs_list;
  };
  
  static const MediaFormatStrict format_codec_mappings[] = {
    { "video/webm", "vorbis,vp8,vp8.0" },
    { "audio/webm", "vorbis" },
    { "audio/wav", "1" }
  };
  
  void MimeUtil::InitializeMimeTypeMaps() {
    for (size_t i = 0; i < arraysize(supported_image_types); ++i)
      image_map_.insert(supported_image_types[i]);
  
    // Initialize the supported non-image types.
    for (size_t i = 0; i < arraysize(supported_non_image_types); ++i)
      non_image_map_.insert(supported_non_image_types[i]);
    for (size_t i = 0; i < arraysize(supported_javascript_types); ++i)
      non_image_map_.insert(supported_javascript_types[i]);
    for (size_t i = 0; i < arraysize(supported_media_types); ++i)
      non_image_map_.insert(supported_media_types[i]);
  
    // Initialize the supported media types.
    for (size_t i = 0; i < arraysize(supported_media_types); ++i)
      media_map_.insert(supported_media_types[i]);
  
    for (size_t i = 0; i < arraysize(supported_javascript_types); ++i)
      javascript_map_.insert(supported_javascript_types[i]);
  
    for (size_t i = 0; i < arraysize(view_source_types); ++i)
      view_source_map_.insert(view_source_types[i]);
  
    for (size_t i = 0; i < arraysize(supported_media_codecs); ++i)
      codecs_map_.insert(supported_media_codecs[i]);
  
    // Initialize the strict supported media types.
    for (size_t i = 0; i < arraysize(format_codec_mappings); ++i) {
      std::vector<std::string> mime_type_codecs;
      ParseCodecString(format_codec_mappings[i].codecs_list,
                       &mime_type_codecs,
                       false);
  
      MimeMappings codecs;
      for (size_t j = 0; j < mime_type_codecs.size(); ++j)
        codecs.insert(mime_type_codecs[j]);
      strict_format_map_[format_codec_mappings[i].mime_type] = codecs;
    }
  }
  
  bool MimeUtil::IsSupportedImageMimeType(const char* mime_type) const {
    return image_map_.find(mime_type) != image_map_.end();
  }
  
  bool MimeUtil::IsSupportedMediaMimeType(const char* mime_type) const {
    return media_map_.find(mime_type) != media_map_.end();
  }
  
  bool MimeUtil::IsSupportedNonImageMimeType(const char* mime_type) const {
    return non_image_map_.find(mime_type) != non_image_map_.end();
  }
  
  bool MimeUtil::IsSupportedJavascriptMimeType(const char* mime_type) const {
    return javascript_map_.find(mime_type) != javascript_map_.end();
  }
  
  bool MimeUtil::IsViewSourceMimeType(const char* mime_type) const {
    return view_source_map_.find(mime_type) != view_source_map_.end();
  }
  
  // Mirrors WebViewImpl::CanShowMIMEType()
  bool MimeUtil::IsSupportedMimeType(const std::string& mime_type) const {
    return (mime_type.compare(0, 6, "image/") == 0 &&
            IsSupportedImageMimeType(mime_type.c_str())) ||
           IsSupportedNonImageMimeType(mime_type.c_str());
  }
  
  bool MimeUtil::MatchesMimeType(const std::string &mime_type_pattern,
                                 const std::string &mime_type) const {
    // verify caller is passing lowercase
    DCHECK_EQ(StringToLowerASCII(mime_type_pattern), mime_type_pattern);
    DCHECK_EQ(StringToLowerASCII(mime_type), mime_type);
  
    // This comparison handles absolute maching and also basic
    // wildcards.  The plugin mime types could be:
    //      application/x-foo
    //      application/*
    //      application/*+xml
    //      *
    if (mime_type_pattern.empty())
      return false;
  
    const std::string::size_type star = mime_type_pattern.find('*');
  
    if (star == std::string::npos)
      return mime_type_pattern == mime_type;
  
    // Test length to prevent overlap between |left| and |right|.
    if (mime_type.length() < mime_type_pattern.length() - 1)
      return false;
  
    const std::string left(mime_type_pattern.substr(0, star));
    const std::string right(mime_type_pattern.substr(star + 1));
  
    if (mime_type.find(left) != 0)
      return false;
  
    if (!right.empty() &&
        mime_type.rfind(right) != mime_type.length() - right.length())
      return false;
  
    return true;
  }
  
  bool MimeUtil::AreSupportedMediaCodecs(
      const std::vector<std::string>& codecs) const {
    for (size_t i = 0; i < codecs.size(); ++i) {
      if (codecs_map_.find(codecs[i]) == codecs_map_.end()) {
        return false;
      }
    }
    return true;
  }
  
  void MimeUtil::ParseCodecString(const std::string& codecs,
                                  std::vector<std::string>* codecs_out,
                                  bool strip) {
    std::string no_quote_codecs;
    TrimString(codecs, "\"", &no_quote_codecs);
    base::SplitString(no_quote_codecs, ',', codecs_out);
  
    if (!strip)
      return;
  
    // Strip everything past the first '.'
    for (std::vector<std::string>::iterator it = codecs_out->begin();
         it != codecs_out->end();
         ++it) {
      size_t found = it->find_first_of('.');
      if (found != std::string::npos)
        it->resize(found);
    }
  }
  
  bool MimeUtil::IsStrictMediaMimeType(const std::string& mime_type) const {
    if (strict_format_map_.find(mime_type) == strict_format_map_.end())
      return false;
    return true;
  }
  
  bool MimeUtil::IsSupportedStrictMediaMimeType(const std::string& mime_type,
      const std::vector<std::string>& codecs) const {
    StrictMappings::const_iterator it = strict_format_map_.find(mime_type);
  
    if (it == strict_format_map_.end())
      return false;
  
    const MimeMappings strict_codecs_map = it->second;
    for (size_t i = 0; i < codecs.size(); ++i) {
      if (strict_codecs_map.find(codecs[i]) == strict_codecs_map.end()) {
        return false;
      }
    }
    return true;
  }
  
  //----------------------------------------------------------------------------
  // Wrappers for the singleton
  //----------------------------------------------------------------------------
  
  bool GetMimeTypeFromExtension(const FilePath::StringType& ext,
                                std::string* mime_type) {
    return g_mime_util.Get().GetMimeTypeFromExtension(ext, mime_type);
  }
  
  bool GetMimeTypeFromFile(const FilePath& file_path, std::string* mime_type) {
    return g_mime_util.Get().GetMimeTypeFromFile(file_path, mime_type);
  }
  
  bool GetPreferredExtensionForMimeType(const std::string& mime_type,
                                        FilePath::StringType* extension) {
    return g_mime_util.Get().GetPreferredExtensionForMimeType(mime_type,
                                                              extension);
  }
  
  bool IsSupportedImageMimeType(const char* mime_type) {
    return g_mime_util.Get().IsSupportedImageMimeType(mime_type);
  }
  
  bool IsSupportedMediaMimeType(const char* mime_type) {
    return g_mime_util.Get().IsSupportedMediaMimeType(mime_type);
  }
  
  bool IsSupportedNonImageMimeType(const char* mime_type) {
    return g_mime_util.Get().IsSupportedNonImageMimeType(mime_type);
  }
  
  bool IsSupportedJavascriptMimeType(const char* mime_type) {
    return g_mime_util.Get().IsSupportedJavascriptMimeType(mime_type);
  }
  
  bool IsViewSourceMimeType(const char* mime_type) {
    return g_mime_util.Get().IsViewSourceMimeType(mime_type);
  }
  
  bool IsSupportedMimeType(const std::string& mime_type) {
    return g_mime_util.Get().IsSupportedMimeType(mime_type);
  }
  
  bool MatchesMimeType(const std::string &mime_type_pattern,
                       const std::string &mime_type) {
    return g_mime_util.Get().MatchesMimeType(mime_type_pattern, mime_type);
  }
  
  bool AreSupportedMediaCodecs(const std::vector<std::string>& codecs) {
    return g_mime_util.Get().AreSupportedMediaCodecs(codecs);
  }
  
  bool IsStrictMediaMimeType(const std::string& mime_type) {
    return g_mime_util.Get().IsStrictMediaMimeType(mime_type);
  }
  
  bool IsSupportedStrictMediaMimeType(const std::string& mime_type,
                                      const std::vector<std::string>& codecs) {
    return g_mime_util.Get().IsSupportedStrictMediaMimeType(mime_type, codecs);
  }
  
  void ParseCodecString(const std::string& codecs,
                        std::vector<std::string>* codecs_out,
                        const bool strip) {
    g_mime_util.Get().ParseCodecString(codecs, codecs_out, strip);
  }
  
  namespace {
  
  // From http://www.w3schools.com/media/media_mimeref.asp and
  // http://plugindoc.mozdev.org/winmime.php
  static const char* kStandardImageTypes[] = {
    "image/bmp",
    "image/cis-cod",
    "image/gif",
    "image/ief",
    "image/jpeg",
    "image/webp",
    "image/pict",
    "image/pipeg",
    "image/png",
    "image/svg+xml",
    "image/tiff",
    "image/x-cmu-raster",
    "image/x-cmx",
    "image/x-icon",
    "image/x-portable-anymap",
    "image/x-portable-bitmap",
    "image/x-portable-graymap",
    "image/x-portable-pixmap",
    "image/x-rgb",
    "image/x-xbitmap",
    "image/x-xpixmap",
    "image/x-xwindowdump"
  };
  static const char* kStandardAudioTypes[] = {
    "audio/aac",
    "audio/aiff",
    "audio/amr",
    "audio/basic",
    "audio/midi",
    "audio/mp3",
    "audio/mp4",
    "audio/mpeg",
    "audio/mpeg3",
    "audio/ogg",
    "audio/vorbis",
    "audio/wav",
    "audio/webm",
    "audio/x-m4a",
    "audio/x-ms-wma",
    "audio/vnd.rn-realaudio",
    "audio/vnd.wave"
  };
  static const char* kStandardVideoTypes[] = {
    "video/avi",
    "video/divx",
    "video/flc",
    "video/mp4",
    "video/mpeg",
    "video/ogg",
    "video/quicktime",
    "video/sd-video",
    "video/webm",
    "video/x-dv",
    "video/x-m4v",
    "video/x-mpeg",
    "video/x-ms-asf",
    "video/x-ms-wmv"
  };
  
  void GetExtensionsFromHardCodedMappings(
      const MimeInfo* mappings,
      size_t mappings_len,
      const std::string& leading_mime_type,
      base::hash_set<FilePath::StringType>* extensions) {
    FilePath::StringType extension;
    for (size_t i = 0; i < mappings_len; ++i) {
      if (StartsWithASCII(mappings[i].mime_type, leading_mime_type, false)) {
        std::vector<string> this_extensions;
        base::SplitStringUsingSubstr(mappings[i].extensions,
                                     ",",
                                     &this_extensions);
        for (size_t j = 0; j < this_extensions.size(); ++j) {
  #if defined(OS_WIN)
          FilePath::StringType extension(UTF8ToWide(this_extensions[j]));
  #else
          FilePath::StringType extension(this_extensions[j]);
  #endif
          extensions->insert(extension);
        }
      }
    }
  }
  
  void GetExtensionsHelper(
      const char** standard_types,
      size_t standard_types_len,
      const std::string& leading_mime_type,
      base::hash_set<FilePath::StringType>* extensions) {
    FilePath::StringType extension;
    for (size_t i = 0; i < standard_types_len; ++i) {
      if (GetPreferredExtensionForMimeType(standard_types[i], &extension))
        extensions->insert(extension);
    }
  
    // Also look up the extensions from hard-coded mappings in case that some
    // supported extensions are not registered in the system registry, like ogg.
    GetExtensionsFromHardCodedMappings(primary_mappings,
                                       arraysize(primary_mappings),
                                       leading_mime_type,
                                       extensions);
  
    GetExtensionsFromHardCodedMappings(secondary_mappings,
                                       arraysize(secondary_mappings),
                                       leading_mime_type,
                                       extensions);
  }
  
  // Note that the elements in the source set will be appended to the target
  // vector.
  template<class T>
  void HashSetToVector(base::hash_set<T>* source, std::vector<T>* target) {
    size_t old_target_size = target->size();
    target->resize(old_target_size + source->size());
    size_t i = 0;
    for (typename base::hash_set<T>::iterator iter = source->begin();
         iter != source->end(); ++iter, ++i) {
      target->at(old_target_size + i) = *iter;
    }
  }
  }
  
  void GetImageExtensions(std::vector<FilePath::StringType>* extensions) {
    base::hash_set<FilePath::StringType> unique_extensions;
    GetExtensionsHelper(kStandardImageTypes,
                        arraysize(kStandardImageTypes),
                        "image/",
                        &unique_extensions);
    HashSetToVector(&unique_extensions, extensions);
  }
  
  void GetAudioExtensions(std::vector<FilePath::StringType>* extensions) {
    base::hash_set<FilePath::StringType> unique_extensions;
    GetExtensionsHelper(kStandardAudioTypes,
                        arraysize(kStandardAudioTypes),
                        "audio/",
                        &unique_extensions);
    HashSetToVector(&unique_extensions, extensions);
  }
  
  void GetVideoExtensions(std::vector<FilePath::StringType>* extensions) {
    base::hash_set<FilePath::StringType> unique_extensions;
    GetExtensionsHelper(kStandardVideoTypes,
                        arraysize(kStandardVideoTypes),
                        "video/",
                        &unique_extensions);
    HashSetToVector(&unique_extensions, extensions);
  }
  
  void GetExtensionsForMimeType(const std::string& mime_type,
                                std::vector<FilePath::StringType>* extensions) {
    base::hash_set<FilePath::StringType> unique_extensions;
    FilePath::StringType extension;
    if (GetPreferredExtensionForMimeType(mime_type, &extension))
      unique_extensions.insert(extension);
  
    // Also look up the extensions from hard-coded mappings in case that some
    // supported extensions are not registered in the system registry, like ogg.
    GetExtensionsFromHardCodedMappings(primary_mappings,
                                       arraysize(primary_mappings),
                                       mime_type,
                                       &unique_extensions);
  
    GetExtensionsFromHardCodedMappings(secondary_mappings,
                                       arraysize(secondary_mappings),
                                       mime_type,
                                       &unique_extensions);
  
    HashSetToVector(&unique_extensions, extensions);
  }
  
  }  // namespace net
  