WebCrypto: Update the key usage names to reflect recent changes to the spec.

Source/core/platform/chromium/support/WebCryptoKey.cpp

Index: Source/core/platform/chromium/support/WebCryptoKey.cpp
diff --git a/Source/core/platform/chromium/support/WebCryptoKey.cpp b/Source/core/platform/chromium/support/WebCryptoKey.cpp
index a239917fd6674bf62d0eee18971552db0a8affab..64e3b9ce780ce1694b281ef794069759387ce928 100644
--- a/Source/core/platform/chromium/support/WebCryptoKey.cpp
+++ b/Source/core/platform/chromium/support/WebCryptoKey.cpp
@@ -39,12 +39,12 @@ namespace WebKit {
 
 class WebCryptoKeyPrivate : public ThreadSafeRefCounted<WebCryptoKeyPrivate> {
 public:
-    WebCryptoKeyPrivate(PassOwnPtr<WebCryptoKeyHandle> handle, WebCryptoKeyType type, bool extractable, const WebCryptoAlgorithm& algorithm, WebCryptoKeyUsageMask keyUsage)
+    WebCryptoKeyPrivate(PassOwnPtr<WebCryptoKeyHandle> handle, WebCryptoKeyType type, bool extractable, const WebCryptoAlgorithm& algorithm, WebCryptoKeyUsageMask usages)
         : handle(handle)
         , type(type)
         , extractable(extractable)
         , algorithm(algorithm)
-        , keyUsage(keyUsage)
+        , usages(usages)
     {
     }
 
@@ -52,13 +52,13 @@ public:
     const WebCryptoKeyType type;
     const bool extractable;
     const WebCryptoAlgorithm algorithm;
-    const WebCryptoKeyUsageMask keyUsage;
+    const WebCryptoKeyUsageMask usages;
 };
 
-WebCryptoKey WebCryptoKey::create(WebCryptoKeyHandle* handle, WebCryptoKeyType type, bool extractable, const WebCryptoAlgorithm& algorithm, WebCryptoKeyUsageMask keyUsage)
+WebCryptoKey WebCryptoKey::create(WebCryptoKeyHandle* handle, WebCryptoKeyType type, bool extractable, const WebCryptoAlgorithm& algorithm, WebCryptoKeyUsageMask usages)
 {
     WebCryptoKey key;
-    key.m_private = adoptRef(new WebCryptoKeyPrivate(adoptPtr(handle), type, extractable, algorithm, keyUsage));
+    key.m_private = adoptRef(new WebCryptoKeyPrivate(adoptPtr(handle), type, extractable, algorithm, usages));
     return key;
 }
 
@@ -82,9 +82,9 @@ const WebCryptoAlgorithm& WebCryptoKey::algorithm() const
     return m_private->algorithm;
 }
 
-WebCryptoKeyUsageMask WebCryptoKey::keyUsage() const
+WebCryptoKeyUsageMask WebCryptoKey::usages() const
 {
-    return m_private->keyUsage;
+    return m_private->usages;
 }
 
 void WebCryptoKey::assign(const WebCryptoKey& other)