We should download text/csv mime types instead of displaying them....

net/base/mime_util_unittest.cc

 // Copyright (c) 2006-2008 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 "base/basictypes.h"
 #include "net/base/mime_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace {
   class MimeUtilTest : public testing::Test {
@@ skipping 47 matching lines @@
     if (rv)
       EXPECT_EQ(mime_type, tests[i].mime_type);
   }
 }
 
 TEST(MimeUtilTest, LookupTypes) {
   EXPECT_EQ(true, net::IsSupportedImageMimeType("image/jpeg"));
   EXPECT_EQ(false, net::IsSupportedImageMimeType("image/lolcat"));
   EXPECT_EQ(true, net::IsSupportedNonImageMimeType("text/html"));
   EXPECT_EQ(false, net::IsSupportedNonImageMimeType("text/virus"));
+
+  EXPECT_EQ(true, net::IsSupportedMimeType("image/jpeg"));
+  EXPECT_EQ(false, net::IsSupportedMimeType("image/lolcat"));
+  EXPECT_EQ(true, net::IsSupportedMimeType("text/html"));
+  EXPECT_EQ(false, net::IsSupportedMimeType("text/virus"));
 }
 
 TEST(MimeUtilTest, MatchesMimeType) {
   EXPECT_EQ(true, net::MatchesMimeType("*", "video/x-mpeg"));
   EXPECT_EQ(true, net::MatchesMimeType("video/*", "video/x-mpeg"));
   EXPECT_EQ(true, net::MatchesMimeType("video/x-mpeg", "video/x-mpeg"));
   EXPECT_EQ(true, net::MatchesMimeType("application/*+xml",
                                              "application/html+xml"));
   EXPECT_EQ(true, net::MatchesMimeType("application/*+xml",
                                              "application/+xml"));
   EXPECT_EQ(true, net::MatchesMimeType("aaa*aaa",
                                              "aaaaaa"));
   EXPECT_EQ(false, net::MatchesMimeType("video/", "video/x-mpeg"));
   EXPECT_EQ(false, net::MatchesMimeType("", "video/x-mpeg"));
   EXPECT_EQ(false, net::MatchesMimeType("", ""));
   EXPECT_EQ(false, net::MatchesMimeType("video/x-mpeg", ""));
   EXPECT_EQ(false, net::MatchesMimeType("application/*+xml",
                                               "application/xml"));
   EXPECT_EQ(false, net::MatchesMimeType("application/*+xml",
                                               "application/html+xmlz"));
   EXPECT_EQ(false, net::MatchesMimeType("application/*+xml",
                                               "applcation/html+xml"));
   EXPECT_EQ(false, net::MatchesMimeType("aaa*aaa",
                                               "aaaaa"));
 }