Move media related mimetype functionality out of net/ and into media/.

content/common/mime_util.cc

+// Copyright 2014 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 "content/common/mime_util.h"
+
+#include <string>
+
+#include "media/base/mime_util.h"
+#include "net/base/mime_util.h"
+
+namespace content {
+
+bool IsSupportedMimeType(const std::string& mime_type) {
+  return net::IsSupportedMimeType(mime_type) ||

[darin (slow to review), 2014/07/24 17:52:53]

the only concern I have is that it could be confusing what version of
IsSupportedMimeType one is to call. i would almost prefer some form of
dependency injection into net's mime_util. you could imagine pushing settings
into it, or set a delegate method for it to call. that way everyone will still
think the truth of mime type info lives in net/base/mime_util.h.

[Ryan Sleevi, 2014/07/24 18:24:09]

I do think it's weird to have the truth of mime type info in //net. There's
really all sorts of lies in it.

For example, if a plugin handles a mime-type, is it supported or not? What about
a CDM (where some of this is coming up w/r/t //media)?

There's actually only one place in //net it's used, and that's whether or not to
download something if it wasn't explicitly requested, and if and only if it's an
explicitly .gz/.tgz file. Which is, well, weird.

+      media::IsSupportedMediaMimeType(mime_type);
+}
+
+}