KeyChain API refinements

Change-Id: I177ab4642e6cd1aa13526c14f0a707175fd79655
diff --git a/keystore/java/android/security/KeyChainException.java b/keystore/java/android/security/KeyChainException.java
new file mode 100644
index 0000000..3953f58
--- /dev/null
+++ b/keystore/java/android/security/KeyChainException.java
@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.security;
+
+/**
+ * Thrown on problems accessing the {@link KeyChain}.
+ *
+ * @hide to be unhidden as part of KeyChain API
+ */
+public class KeyChainException extends Exception {
+
+    /**
+     * Constructs a new {@code KeyChainException} that includes the
+     * current stack trace.
+     */
+    public KeyChainException() {
+    }
+
+    /**
+     * Constructs a new {@code KeyChainException} with the current stack
+     * trace and the specified detail message.
+     *
+     * @param detailMessage
+     *            the detail message for this exception.
+     */
+    public KeyChainException(String detailMessage) {
+        super(detailMessage);
+    }
+
+    /**
+     * Constructs a new {@code KeyChainException} with the current stack
+     * trace, the specified detail message and the specified cause.
+     *
+     * @param message
+     *            the detail message for this exception.
+     * @param cause
+     *            the cause of this exception, may be {@code null}.
+     */
+    public KeyChainException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    /**
+     * Constructs a new {@code KeyChainException} with the current stack
+     * trace and the specified cause.
+     *
+     * @param cause
+     *            the cause of this exception, may be {@code null}.
+     */
+    public KeyChainException(Throwable cause) {
+        super((cause == null ? null : cause.toString()), cause);
+    }
+}