Cleanup: Delete sk_tools::make_filepath() in favor of SkOSPath::SkPathJoin().

tools/picture_utils.cpp

Index: tools/picture_utils.cpp
diff --git a/tools/picture_utils.cpp b/tools/picture_utils.cpp
index 850e21f8e7de4e63c71caad67b6f805ba13e9eed..d88d922af966b7348c169cb567912e0039da8543 100644
--- a/tools/picture_utils.cpp
+++ b/tools/picture_utils.cpp
@@ -41,15 +41,6 @@ namespace sk_tools {
         }
     }
 
-    void make_filepath(SkString* path, const SkString& dir, const SkString& name) {
-        size_t len = dir.size();
-        path->set(dir);
-        if (0 < len  && '/' != dir[len - 1]) {
-            path->append("/");
-        }
-        path->append(name);
-    }
-
     bool is_percentage(const char* const string) {
         SkString skString(string);
         return skString.endsWith("%");