[WebCrypto] Use Deprecation instead of UseCounter

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

 // Copyright 2016 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.
 
 #include "core/frame/Deprecation.h"
 
 #include "core/dom/Document.h"
 #include "core/dom/ExecutionContext.h"
 #include "core/frame/FrameConsole.h"
 #include "core/frame/FrameHost.h"
@@ skipping 405 matching lines @@
 
     case UseCounter::CSSZoomDocument:
       return willBeRemoved("\"zoom: document\"", M59, "4997605029314560");
 
     case UseCounter::SelectionAddRangeIntersect:
       return "The behavior that Selection.addRange() merges existing Range and "
              "the specified Range was removed. See "
              "https://www.chromestatus.com/features/6680566019653632 for more "
              "details.";
 
+    case UseCounter::SubtleCryptoOnlyStrictSecureContextCheckFailed:
+      return "WebCrypto requires secure origin to be used.";

[Mike West, 2017/02/23 15:39:53]

How about something like:

```
return String::format(
  "Web Crypto API usage inside secure frames with non-secure ancestors is
deprecated."
  "The API will no longer be exposed in these contexts as of %s. See "
  "[link to chromestatus entry] for more details.",
  milestoneString(M59));
```

+
     // Features that aren't deprecated don't have a deprecation message.
     default:
       return String();
   }
 }
 
 }  // namespace blink