Eliminate one copy of replace_char() function.

tools/picture_utils.cpp

Index: tools/picture_utils.cpp
diff --git a/tools/picture_utils.cpp b/tools/picture_utils.cpp
index 5c120b010d98ca56ebd7fe079eb01c0740190f36..8f2faa941dec7f22807623e7f5085a6d4595743f 100644
--- a/tools/picture_utils.cpp
+++ b/tools/picture_utils.cpp
@@ -30,17 +30,6 @@ namespace sk_tools {
         }
     }
 
-    void replace_char(SkString* str, const char oldChar, const char newChar) {
-        if (NULL == str) {
-            return;
-        }
-        for (size_t i = 0; i < str->size(); ++i) {
-            if (oldChar == str->operator[](i)) {
-                str->operator[](i) = newChar;
-            }
-        }
-    }
-
     bool is_percentage(const char* const string) {
         SkString skString(string);
         return skString.endsWith("%");