Use std::unique_ptr to pass around WebCryptoDigestor.

third_party/WebKit/public/platform/WebCrypto.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 20 matching lines @@
 #ifndef WebCrypto_h
 #define WebCrypto_h
 
 #include "WebCommon.h"
 #include "WebCryptoAlgorithm.h"
 #include "WebCryptoKey.h"
 #include "WebPrivatePtr.h"
 #include "WebString.h"
 #include "WebVector.h"
 
+#include <memory>
+
 #if INSIDE_BLINK
 #include "platform/heap/Handle.h"
 #endif
 
 namespace blink {
 
 class CryptoResult;
 class CryptoResultCancel;
 class WebString;
 
@@ skipping 156 matching lines @@
     virtual void importKey(WebCryptoKeyFormat, const unsigned char* keyData, unsigned keyDataSize, const WebCryptoAlgorithm&, bool extractable, WebCryptoKeyUsageMask, WebCryptoResult result) { result.completeWithError(WebCryptoErrorTypeNotSupported, ""); }
     virtual void exportKey(WebCryptoKeyFormat, const WebCryptoKey&, WebCryptoResult result) { result.completeWithError(WebCryptoErrorTypeNotSupported, ""); }
     virtual void wrapKey(WebCryptoKeyFormat, const WebCryptoKey& key, const WebCryptoKey& wrappingKey, const WebCryptoAlgorithm&, WebCryptoResult result) { result.completeWithError(WebCryptoErrorTypeNotSupported, ""); }
     virtual void unwrapKey(WebCryptoKeyFormat, const unsigned char* wrappedKey, unsigned wrappedKeySize, const WebCryptoKey&, const WebCryptoAlgorithm& unwrapAlgorithm, const WebCryptoAlgorithm& unwrappedKeyAlgorithm, bool extractable, WebCryptoKeyUsageMask, WebCryptoResult result) { result.completeWithError(WebCryptoErrorTypeNotSupported, ""); }
     virtual void deriveBits(const WebCryptoAlgorithm&, const WebCryptoKey&, unsigned length, WebCryptoResult result) { result.completeWithError(WebCryptoErrorTypeNotSupported, ""); }
     virtual void deriveKey(const WebCryptoAlgorithm& algorithm, const WebCryptoKey& baseKey, const WebCryptoAlgorithm& importAlgorithm, const WebCryptoAlgorithm& keyLengthAlgorithm, bool extractable, WebCryptoKeyUsageMask, WebCryptoResult result) { result.completeWithError(WebCryptoErrorTypeNotSupported, ""); }
 
     // This is the exception to the "Completing the request" guarantees
     // outlined above. This is useful for Blink internal crypto and is not part
     // of the WebCrypto standard. createDigestor must provide the result via
-    // the WebCryptoDigestor object synchronously. createDigestor may return 0
-    // if it fails to create a WebCryptoDigestor. If it succeeds, the
-    // WebCryptoDigestor returned by createDigestor must be freed by the
-    // caller.
-    virtual WebCryptoDigestor* createDigestor(WebCryptoAlgorithmId algorithmId) { return nullptr; }
+    // the WebCryptoDigestor object synchronously. This will never return null.
+    virtual std::unique_ptr<WebCryptoDigestor> createDigestor(WebCryptoAlgorithmId algorithmId) { return nullptr; }
 
     // -----------------------
     // Structured clone
     // -----------------------
     //
     // deserializeKeyForClone() and serializeKeyForClone() are used for
     // implementing structured cloning of WebCryptoKey.
     //
     // Blink is responsible for saving and restoring all of the attributes of
     // WebCryptoKey EXCEPT for the actual key data:
@@ skipping 36 matching lines @@
     // Returns true on success.
     virtual bool serializeKeyForClone(const WebCryptoKey&, WebVector<unsigned char>&) { return false; }
 
 protected:
     virtual ~WebCrypto() { }
 };
 
 } // namespace blink
 
 #endif // WebCrypto_h