Implement ChromeOS mime type extension mappings.

net/base/platform_mime_util_chromeos.cc

+// Copyright 2015 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 "net/base/platform_mime_util.h"
+
+#include "base/logging.h"
+#include "net/base/mime_util.h"
+
+namespace net {
+
+namespace {
+
+static const MimeInfo mimetype_extension_mapping[] = {
+    {"text/calendar", "ics"},
+    {"application/epub+zip", "epub"},
+};
+}

[eroman, 2015/05/15 09:05:33]

Add comment:
  // namespace

[yawano, 2015/05/18 08:59:44]

Done.

+
+// Since ChromeOS does not have mimetype-extension database in it, we use

[eroman, 2015/05/15 09:05:33]

Please provide some extra details in this comment -- explain how on Linux it
uses xdg_mime and /usr/share/mime, but ChromeOS does not have /usr/share/mime
(and did you figure out *why* it does not have that?)

[yawano, 2015/05/18 08:59:44]

Done.

I asked this on ML but I couldn't figure out why. It seems that it just doesn't
include it for now. -
https://groups.google.com/a/chromium.org/d/msg/chromium-os-dev/mCgDTj8AJqs/LQ...

+// |mimetype_extension_mapping| to resolve mime type.
+bool PlatformMimeUtil::GetPlatformMimeTypeFromExtension(
+    const base::FilePath::StringType& ext,
+    std::string* mime_type) const {
+  const char* result =
+      net::FindMimeType(mimetype_extension_mapping,

[eroman, 2015/05/15 09:05:33]

no need for net:: prefix

[yawano, 2015/05/18 08:59:44]

Acknowledged.

+                        arraysize(mimetype_extension_mapping), ext.c_str());

[eroman, 2015/05/15 09:05:33]

It would be better if didn't have to take .c_str() of |ext|.
It is probably possible for |ext| to contain embedded \0 in which case using
.c_str() will not be correct. I guess we already have this problem in mime_util
then...

[yawano, 2015/05/18 08:59:43]

I think an extension which contains null character should not be valid. Changed
to reject such input in GetMimeTypeFromExtensionHelper.

Note: In the current usage, FindMimeType don't get an input which contains null
character. base::FilePath cuts string not to contain null character. e.g. If
input is png\0css, base::FilePath is initialized as png.

+  if (result) {
+    *mime_type = result;
+    return true;
+  }
+
+  return false;
+}
+}

[eroman, 2015/05/15 09:05:33]

add comment:
// namespace net

[yawano, 2015/05/18 08:59:44]

Acknowledged.