Refactor the interface for generating keys.

content/child/webcrypto/openssl/hmac_openssl.cc

Index: content/child/webcrypto/openssl/hmac_openssl.cc
diff --git a/content/child/webcrypto/openssl/hmac_openssl.cc b/content/child/webcrypto/openssl/hmac_openssl.cc
index c7b4b37686834578726b7a1e2363d61f47dd82dd..f618501c02b7cbecacf676bb4cb9fde31d0d1ac7 100644
--- a/content/child/webcrypto/openssl/hmac_openssl.cc
+++ b/content/child/webcrypto/openssl/hmac_openssl.cc
@@ -70,15 +70,19 @@ class HmacImplementation : public AlgorithmImplementation {
  public:
   HmacImplementation() {}
 
-  virtual Status GenerateSecretKey(const blink::WebCryptoAlgorithm& algorithm,
-                                   bool extractable,
-                                   blink::WebCryptoKeyUsageMask usage_mask,
-                                   blink::WebCryptoKey* key) const override {
+  virtual Status GenerateKey(const blink::WebCryptoAlgorithm& algorithm,
+                             bool extractable,
+                             blink::WebCryptoKeyUsageMask usage_mask,
+                             GenerateKeyResult* result) const override {
+    Status status = CheckKeyCreationUsages(kAllKeyUsages, usage_mask);
+    if (status.IsError())
+      return status;
+
     const blink::WebCryptoHmacKeyGenParams* params =
         algorithm.hmacKeyGenParams();
 
     unsigned int keylen_bits = 0;
-    Status status = GetHmacKeyGenLengthInBits(params, &keylen_bits);
+    status = GetHmacKeyGenLengthInBits(params, &keylen_bits);
     if (status.IsError())
       return status;
 
@@ -87,7 +91,7 @@ class HmacImplementation : public AlgorithmImplementation {
                                     extractable,
                                     usage_mask,
                                     keylen_bits / 8,
-                                    key);
+                                    result);
   }
 
   virtual Status VerifyKeyUsagesBeforeImportKey(
@@ -102,11 +106,6 @@ class HmacImplementation : public AlgorithmImplementation {
     }
   }
 
-  virtual Status VerifyKeyUsagesBeforeGenerateKey(
-      blink::WebCryptoKeyUsageMask usage_mask) const override {
-    return CheckKeyCreationUsages(kAllKeyUsages, usage_mask);
-  }
-
   virtual Status ImportKeyRaw(const CryptoData& key_data,
                               const blink::WebCryptoAlgorithm& algorithm,
                               bool extractable,