Add 'audio/aac' mimetype support

In old implementation, 'audio/aac' is not supported when using
IsSupportedMediaMimeType to check. That will block aac audio to play.

Review URL: https://codereview.chromium.org/895523002

Cr-Commit-Position: refs/heads/master@{#314952}

net/base/mime_util.cc

@@ -359,6 +359,7 @@ static const char* const proprietary_media_types[] = {
   "audio/mp3",
   "audio/x-mp3",
   "audio/mpeg",
+  "audio/aac",
 
 #if defined(ENABLE_MPEG2TS_STREAM_PARSER)
   // MPEG-2 TS.

net/base/mime_util_unittest.cc

@@ -231,6 +231,7 @@ TEST(MimeUtilTest, CommonMediaMimeType) {
   EXPECT_TRUE(IsSupportedMediaMimeType("audio/mp3"));
   EXPECT_TRUE(IsSupportedMediaMimeType("audio/x-mp3"));
   EXPECT_TRUE(IsSupportedMediaMimeType("audio/mpeg"));
+  EXPECT_TRUE(IsSupportedMediaMimeType("audio/aac"));
 
 #if defined(ENABLE_MPEG2TS_STREAM_PARSER)
   EXPECT_TRUE(IsSupportedMediaMimeType("video/mp2t"));
@@ -246,6 +247,7 @@ TEST(MimeUtilTest, CommonMediaMimeType) {
   EXPECT_FALSE(IsSupportedMediaMimeType("audio/mp3"));
   EXPECT_FALSE(IsSupportedMediaMimeType("audio/x-mp3"));
   EXPECT_FALSE(IsSupportedMediaMimeType("audio/mpeg"));
+  EXPECT_FALSE(IsSupportedMediaMimeType("audio/aac"));
 #endif  // USE_PROPRIETARY_CODECS
   EXPECT_FALSE(IsSupportedMediaMimeType("video/mp3"));