Fix memory leak in build example

site/user/sample/building.md

Index: site/user/sample/building.md
diff --git a/site/user/sample/building.md b/site/user/sample/building.md
index 92865d17b8a57b8b724452334d3bf5afe9ca4d79..2fed87f374c84c52e9654afe13b24f16b2ea39fe 100644
--- a/site/user/sample/building.md
+++ b/site/user/sample/building.md
@@ -260,10 +260,10 @@ int main(int argc, char** argv) {
   SkPaint paint;
   paint.setColor(SK_ColorRED);
 
-  SkString* str = new SkString();
-  paint.toString(str);
+  SkString str;
+  paint.toString(&str);
 
-  fprintf(stdout, "%s\n", str->c_str());
+  fprintf(stdout, "%s\n", str.c_str());
 
   return 0;
 }
@@ -317,4 +317,3 @@ sync.
 
 Adding the above to the end of DEPS and running gclient sync should show the
 GYP files being updated at the end of the sync procedure.
-