Refactor the interface for generating keys.

content/child/webcrypto/generate_key_result.h

+// Copyright 2014 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.
+
+#ifndef CONTENT_CHILD_WEBCRYPTO_GENERATE_KEY_RESULT_H_
+#define CONTENT_CHILD_WEBCRYPTO_GENERATE_KEY_RESULT_H_
+
+#include "content/common/content_export.h"
+#include "third_party/WebKit/public/platform/WebCrypto.h"
+
+namespace content {
+
+namespace webcrypto {
+
+// This is the result object when generating keys. It encapsulates either a
+// secret key, or a public/private key pair.
+class CONTENT_EXPORT GenerateKeyResult {
+ public:
+  enum Type {
+    // An empty (or "null") result.
+    TYPE_NULL,
+
+    // The result is a secret key, accessible through secret_key()
+    TYPE_SECRET_KEY,
+
+    // The result is a public/private key pair, accessible through public_key()
+    // and private_key()
+    TYPE_PUBLIC_PRIVATE_KEY_PAIR
+  };
+
+  // Initializes a "null" instance.
+  GenerateKeyResult();
+
+  Type type() const;
+
+  // Changes the type of the result. To subsequently assign the key(s) use the
+  // mutable_* methods.
+  void set_type(Type type);
+
+  const blink::WebCryptoKey& secret_key() const;
+  const blink::WebCryptoKey& public_key() const;
+  const blink::WebCryptoKey& private_key() const;
+
+  blink::WebCryptoKey* mutable_secret_key();
+  blink::WebCryptoKey* mutable_public_key();
+  blink::WebCryptoKey* mutable_private_key();
+
+  // Sends the key(s) to the Blink result. Should not be called for "null"
+  // results.
+  void Complete(blink::WebCryptoResult* out) const;
+
+ private:
+  Type type_;
+
+  blink::WebCryptoKey secret_key_;
+  blink::WebCryptoKey public_key_;
+  blink::WebCryptoKey private_key_;

[Ryan Sleevi, 2014/10/17 21:01:58]

since blink::WebCryptoKey types are direct-assignable (you relied on this in the
old and new code), why have mutable_secret_key instead of set_secret_key? The
latter makes it clear it's an assignment, while the former allows you to mux
around with the internal state beyond assignment (which none of the files seem
to do / need)

[eroman, 2014/10/17 22:43:12]

Done. I agree mutable_ was a bit odd and not idiomatic.

... I don't remember what my thinking was at time time. Probably I saw that as
the most direct translation when refactoring, or was overly concerned with
copying.

+};
+
+}  // namespace webcrypto
+
+}  // namespace content
+
+#endif  // CONTENT_CHILD_WEBCRYPTO_GENERATE_KEY_RESULT_H_