[webcrypto] Match the error handling defined by the spec.

Source/modules/crypto/CryptoResultImpl.h

 /*
  * Copyright (C) 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 25 matching lines @@
 #include "core/dom/ContextLifecycleObserver.h"
 #include "core/platform/CryptoResult.h"
 #include "public/platform/WebCrypto.h"
 #include "wtf/Assertions.h"
 #include "wtf/Forward.h"
 #include "wtf/Threading.h"
 
 namespace WebCore {
 
 class ScriptPromiseResolver;
+class ScriptState;
 
 // Wrapper around a Promise to notify completion of the crypto operation.
 // Platform cannot know about Promises which are declared in bindings.
 class CryptoResultImpl FINAL : public CryptoResult, public ContextLifecycleObserver {
 public:
     ~CryptoResultImpl();
 
     static PassRefPtr<CryptoResultImpl> create(ScriptPromise);
 
     virtual void completeWithError() OVERRIDE;
+    virtual void completeWithError(const blink::WebString&) OVERRIDE;
     virtual void completeWithBuffer(const blink::WebArrayBuffer&) OVERRIDE;
     virtual void completeWithBoolean(bool) OVERRIDE;
     virtual void completeWithKey(const blink::WebCryptoKey&) OVERRIDE;
     virtual void completeWithKeyPair(const blink::WebCryptoKey& publicKey, const blink::WebCryptoKey& privateKey) OVERRIDE;
 
 private:
     CryptoResultImpl(ExecutionContext*, ScriptPromise);
     void finish();
     void CheckValidThread() const;
 
@@ skipping 10 matching lines @@
 
 #if !ASSERT_DISABLED
     ThreadIdentifier m_owningThread;
     bool m_finished;
 #endif
 };
 
 } // namespace WebCore
 
 #endif