Deprecate fetching stylesheets with unsupported type

third_party/WebKit/Source/core/frame/UseCounter.cpp

 /*
  * Copyright (C) 2012 Google, Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 954 matching lines @@
 
     case RTCPeerConnectionCreateAnswerLegacyNoFailureCallback:
         return "RTCPeerConnection.CreateAnswer without a failure callback is deprecated. The failure callback will be a required parameter in M50. See https://www.chromestatus.com/feature/5663288008376320 for more details";
 
     case RTCPeerConnectionCreateOfferLegacyNoFailureCallback:
         return "RTCPeerConnection.CreateOffer without a failure callback is deprecated. The failure callback will be a required parameter in M50. See https://www.chromestatus.com/feature/5663288008376320 for more details";
 
     case ObjectObserve:
         return willBeRemoved("'Object.observe'", 50, "6147094632988672");
 
+    case NonCSSStyleSheetType:
+        return String::format("Using stylesheet links with types other than 'text/css' is deprecated and will be removed in %s.", milestoneString(50));
+
     // Features that aren't deprecated don't have a deprecation message.
     default:
         return String();
     }
 }
 
 void UseCounter::count(CSSParserMode cssParserMode, CSSPropertyID feature)
 {
     ASSERT(feature >= firstCSSProperty);
     ASSERT(feature <= lastUnresolvedCSSProperty);
@@ skipping 27 matching lines @@
 UseCounter* UseCounter::getFrom(const StyleSheetContents* sheetContents)
 {
     // FIXME: We may want to handle stylesheets that have multiple owners
     //        https://crbug.com/242125
     if (sheetContents && sheetContents->hasSingleOwnerNode())
         return getFrom(sheetContents->singleOwnerDocument());
     return 0;
 }
 
 } // namespace blink