Move the IsSupported* mime functions out of //net and into //components/mime_util

components/mime_util/mime_util.gyp

-# Copyright 2013 The Chromium Authors. All rights reserved.
+# 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.
 
 {
   'targets': [
     {
-      'target_name': 'perf_test',
+      # GN version: //components/mime_util/mime_util
+      'target_name': 'mime_util',
       'type': 'static_library',
-      'sources': [
-        'perf_test.cc',
-      ],
       'dependencies': [
         '../../base/base.gyp:base',
+        '../../net/net.gyp:net',
       ],
-    },
+      'sources': [
+        'mime_util.cc',
+        'mime_util.h',
+      ],
+    }
   ],
 }