Clarify JavaDoc for WebView.loadData()

Bug: 5461416
Change-Id: I3f0955677ea64bb4073c97aabea34096298cd710

Author: Steve Block

core/java/android/webkit/WebView.java

@@ -801,11 +801,13 @@ public void postUrl(String url, byte[] postData) {
      * #loadDataWithBaseURL(String,String,String,String,String)
      * loadDataWithBaseURL()} with an appropriate base URL.
      * <p>
-     * If the value of the encoding parameter is 'base64', then the data must
-     * be encoded as base64. Otherwise, the data must use ASCII encoding for
+     * The encoding parameter specifies whether the data is base64 or URL
+     * encoded. If the data is base64 encoded, the value of the encoding
+     * parameter must be 'base64'. For all other values of the parameter,
+     * including null, it is assumed that the data uses ASCII encoding for
      * octets inside the range of safe URL characters and use the standard %xx
-     * hex encoding of URLs for octets outside that range. For example,
-     * '#', '%', '\', '?' should be replaced by %23, %25, %27, %3f respectively.
+     * hex encoding of URLs for octets outside that range. For example, '#',
+     * '%', '\', '?' should be replaced by %23, %25, %27, %3f respectively.
      * <p>
      * The 'data' scheme URL formed by this method uses the default US-ASCII
      * charset. If you need need to set a different charset, you should form a