[net] Remove logic for fixing up Gzip encoding type for downloads.

net/filter/filter.cc

Index: net/filter/filter.cc
diff --git a/net/filter/filter.cc b/net/filter/filter.cc
index af4e55128449818c72be04a0c734ed1d1eb5096a..719737daffc1813ad4884d47f2cac46512691035 100644
--- a/net/filter/filter.cc
+++ b/net/filter/filter.cc
@@ -24,11 +24,8 @@
 #include "net/filter/filter.h"
 
 #include "base/files/file_path.h"
-#include "base/metrics/histogram_macros.h"
 #include "base/strings/string_util.h"
-#include "net/base/filename_util_unsafe.h"
 #include "net/base/io_buffer.h"
-#include "net/base/mime_util.h"
 #include "net/base/sdch_net_log_params.h"
 #include "net/filter/gzip_filter.h"
 #include "net/filter/sdch_filter.h"
@@ -49,9 +46,6 @@ const char kSdch[]         = "sdch";
 // more information, see Firefox's nsHttpChannel::ProcessNormal.
 
 // Mime types:
-const char kApplicationXGzip[]     = "application/x-gzip";
-const char kApplicationGzip[]      = "application/gzip";
-const char kApplicationXGunzip[]   = "application/x-gunzip";
 const char kTextHtml[]             = "text/html";
 
 // Buffer size allocated when de-compressing data.
@@ -204,32 +198,6 @@ Filter::FilterType Filter::ConvertEncodingToType(
   return type_id;
 }
 
-namespace {
-
-// Result of running FixupEncodingTypes with a Content-Encoding of gzip. This
-// enum is used for UMA and is available in histograms.xml as
-// GzipEncodingFixupResult.
-enum GzipEncodingFixupResult {
-  GZIP_ENCODING_LEFT_AS_IS = 0,
-
-  // Cleared because a resource with a GZIP MIME type was being transferred with
-  // a Content-Encoding of gzip.
-  GZIP_ENCODING_CLEARED_DUE_TO_GZIP_MIME_TYPE = 1,
-
-  // Cleared because the resource is known to be a download and the resulting
-  // file had a filename that indicating that the contents are GZIP.
-  GZIP_ENCODING_CLEARED_DUE_TO_DOWNLOAD_OF_GZIP_FILE = 2,
-
-  // Cleared because the resource is not a handled MIME type (and hence will be
-  // downloaded), and the predicted filename is one that indicates the contents
-  // to be GZIP.
-  GZIP_ENCODING_CLEARED_DUE_TO_UNHANDLED_GZIP_NAME = 3,
-
-  GZIP_ENCODING_FIXUP_RESULT_MAX_ENTRIES
-};
-
-}  // namespace
-
 // static
 void Filter::FixupEncodingTypes(
     const FilterContext& filter_context,
@@ -238,60 +206,6 @@ void Filter::FixupEncodingTypes(
   bool success = filter_context.GetMimeType(&mime_type);
   DCHECK(success || mime_type.empty());
 
-  if ((1 == encoding_types->size()) &&
-      (FILTER_TYPE_GZIP == encoding_types->front())) {
-    GzipEncodingFixupResult fixup_result = GZIP_ENCODING_LEFT_AS_IS;
-    if (LowerCaseEqualsASCII(mime_type, kApplicationXGzip) ||
-        LowerCaseEqualsASCII(mime_type, kApplicationGzip) ||
-        LowerCaseEqualsASCII(mime_type, kApplicationXGunzip)) {
-      // The server has told us that it sent us gziped content with a gzip
-      // content encoding. Sadly, Apache mistakenly sets these headers for all
-      // .gz files. We match Firefox's nsHttpChannel::ProcessNormal and ignore
-      // the Content-Encoding here.
-      encoding_types->clear();
-      fixup_result = GZIP_ENCODING_CLEARED_DUE_TO_GZIP_MIME_TYPE;
-    }
-
-    GURL url;
-    std::string disposition;
-    success = filter_context.GetURL(&url);
-    DCHECK(success);
-    filter_context.GetContentDisposition(&disposition);
-    // Don't supply a MIME type here, since that may cause disk IO.
-    base::FilePath::StringType extension =
-        GenerateFileExtensionUnsafe(url, disposition, "UTF-8", "", "", "");
-
-    if (filter_context.IsDownload()) {
-      // We don't want to decompress gzipped files when the user explicitly
-      // asks to download them.
-      // For the case of svgz files, we use the extension to distinguish
-      // between svgz files and svg files compressed with gzip by the server.
-      // When viewing a .svgz file, we need to uncompress it, but we don't
-      // want to do that when downloading.
-      // See Firefox's nonDecodableExtensions in nsExternalHelperAppService.cpp
-      if (EndsWith(extension, FILE_PATH_LITERAL(".gz"), false) ||
-          LowerCaseEqualsASCII(extension, ".tgz") ||
-          LowerCaseEqualsASCII(extension, ".svgz")) {
-        encoding_types->clear();
-        fixup_result = GZIP_ENCODING_CLEARED_DUE_TO_DOWNLOAD_OF_GZIP_FILE;
-      }
-    } else {
-      // When the user does not explicitly ask to download a file, if we get a
-      // supported mime type, then we attempt to decompress in order to view it.
-      // However, if it's not a supported mime type, then we will attempt to
-      // download it, and in that case, don't decompress .gz/.tgz files.
-      if ((EndsWith(extension, FILE_PATH_LITERAL(".gz"), false) ||
-           LowerCaseEqualsASCII(extension, ".tgz")) &&
-          !IsSupportedMimeType(mime_type)) {
-        encoding_types->clear();
-        fixup_result = GZIP_ENCODING_CLEARED_DUE_TO_UNHANDLED_GZIP_NAME;
-      }
-    }
-
-    UMA_HISTOGRAM_ENUMERATION("Net.GzipEncodingFixupResult", fixup_result,
-                              GZIP_ENCODING_FIXUP_RESULT_MAX_ENTRIES);
-  }
-
   // If the request was for SDCH content, then we might need additional fixups.
   if (!filter_context.SdchDictionariesAdvertised()) {
     // It was not an SDCH request, so we'll just record stats.