Added [SecureContext] to the subtle attribute

third_party/WebKit/Source/modules/crypto/Crypto.idl

 /*
  * Copyright (C) 2011 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
@@ skipping 15 matching lines @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 // https://w3c.github.io/webcrypto/Overview.html#crypto-interface
 
 [
     Exposed=(Window,Worker)
 ] interface Crypto {
     [RaisesException, MeasureAs=CryptoGetRandomValues] ArrayBufferView getRandomValues(ArrayBufferView array);
 
-    readonly attribute SubtleCrypto subtle;
+    [SecureContext] readonly attribute SubtleCrypto subtle;

[Mike West, 2017/04/24 14:19:22]

This should also let us remove a few other things:

1.  The `SecureContextCheck` enum from `ExecutionContext`, as I believe this API
is the only one that uses `kWebCryptoSecureContextCheck`. Since we'll now only
have one code-path, we can drop the enum entirely from the codebase.

2.  The `CanAccessWebCrypto` check from `SubtleCrypto.cpp` (you can replace it
with DCHECKs if you like, but I think we can just drop it entirely and rely on
the generated IDL checks).

3.  The `kSubtleCryptoOnlyStrictSecureContextCheckFailed` UseCounter enum value.

 };