Fix mime type mappings when the unified media pipeline is enabled.

content/child/runtime_features.cc

Index: content/child/runtime_features.cc
diff --git a/content/child/runtime_features.cc b/content/child/runtime_features.cc
index 1ad1981e747d47b6a7888bd614a4e2d5be45e928..b9fed49d30ab6f9e58bc32de6c3c7992254b49d5 100644
--- a/content/child/runtime_features.cc
+++ b/content/child/runtime_features.cc
@@ -31,9 +31,8 @@ namespace content {
 
 static void SetRuntimeFeatureDefaultsForPlatform() {
 #if defined(OS_ANDROID)
-  // MSE/EME implementation needs Android MediaCodec API.
+  // EME implementation needs Android MediaCodec API.
   if (!media::MediaCodecUtil::IsMediaCodecAvailable()) {
-    WebRuntimeFeatures::enableMediaSource(false);
     WebRuntimeFeatures::enablePrefixedEncryptedMedia(false);
     WebRuntimeFeatures::enableEncryptedMedia(false);
   }