Update the deprecation message for prefixed EME APIs.

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 848 matching lines @@
 
     case RangeCompareNode:
         return replacedBy("Range.compareNode()", "Range.compareBoundaryPoints()");
 
     case RangeExpand:
         return replacedBy("Range.expand()", "Selection.modify()");
 
     case PrefixedMediaAddKey:
     case PrefixedMediaGenerateKeyRequest:
     case PrefixedMediaCancelKeyRequest:
-        return "The prefixed Encrypted Media Extensions APIs are deprecated and will be removed soon. Please use 'navigator.requestMediaKeySystemAccess()' instead.";
+        return "The prefixed Encrypted Media Extensions APIs are deprecated and will be removed in M46 (beta around September 2015). Please use 'navigator.requestMediaKeySystemAccess()' instead.";
 
     case CanPlayTypeKeySystem:
-        return "canPlayType()'s 'keySystem' parameter is deprecated and will be removed soon. Please use 'navigator.requestMediaKeySystemAccess()' instead.";
+        return "canPlayType()'s 'keySystem' parameter is deprecated and will be ignored in M46 (beta around September 2015). Please use 'navigator.requestMediaKeySystemAccess()' instead.";
 
     case SVGSVGElementForceRedraw:
         return "'SVGSVGElement.forceRedraw()' is deprecated, please do not use it. It is a no-op, as per SVG2 (https://svgwg.org/svg2-draft/struct.html#__svg__SVGSVGElement__forceRedraw).";
 
     case SVGSVGElementSuspendRedraw:
         return "'SVGSVGElement.suspendRedraw()' is deprecated, please do not use it. It is a no-op, as per SVG2 (https://svgwg.org/svg2-draft/struct.html#__svg__SVGSVGElement__suspendRedraw).";
 
     case SVGSVGElementUnsuspendRedraw:
         return "'SVGSVGElement.unsuspendRedraw()' is deprecated, please do not use it. It is a no-op, as per SVG2 (https://svgwg.org/svg2-draft/struct.html#__svg__SVGSVGElement__unsuspendRedraw).";
 
@@ skipping 69 matching lines @@
 UseCounter* UseCounter::getFrom(const StyleSheetContents* sheetContents)
 {
     // FIXME: We may want to handle stylesheets that have multiple owners
     //        http://crbug.com/242125
     if (sheetContents && sheetContents->hasSingleOwnerNode())
         return getFrom(sheetContents->singleOwnerDocument());
     return 0;
 }
 
 } // namespace blink