DOC CHANGE: Add javadoc to ClipboardManager

Change-Id: Ib499952c45f3448897a2876ed7a7edd5c3dfebfd

Author: Joe Malin

core/java/android/content/ClipboardManager.java

@@ -70,7 +70,20 @@ public void handleMessage(Message msg) {
         }
     };
 
+    /**
+     * Defines a listener callback that is invoked when the primary clip on the clipboard changes.
+     * Objects that want to register a listener call
+     * {@link android.content.ClipboardManager#addPrimaryClipChangedListener(OnPrimaryClipChangedListener)
+     * addPrimaryClipChangedListener()} with an
+     * object that implements OnPrimaryClipChangedListener.
+     *
+     */
     public interface OnPrimaryClipChangedListener {
+
+        /**
+         * Callback that is invoked by {@link android.content.ClipboardManager} when the primary
+         * clip changes.
+         */
         void onPrimaryClipChanged();
     }