Update code to use helper function for better readability/searching.

src/ports/SkXMLParser_tinyxml.cpp

Index: src/ports/SkXMLParser_tinyxml.cpp
diff --git a/src/ports/SkXMLParser_tinyxml.cpp b/src/ports/SkXMLParser_tinyxml.cpp
index f357592b296a0508377d4a3221b7d097ad7661c1..5f9f3a68de8d54892d16975a5d00c77ba002ebc1 100644
--- a/src/ports/SkXMLParser_tinyxml.cpp
+++ b/src/ports/SkXMLParser_tinyxml.cpp
@@ -58,7 +58,7 @@ static bool load_buf(SkXMLParser* parser, const char buf[])
 
 bool SkXMLParser::parse(SkStream& stream)
 {
-    size_t size = stream.read(NULL, 0);
+    size_t size = stream.getLength();
 
     SkAutoMalloc    buffer(size + 1);
     char*           buf = (char*)buffer.get();