Eliminate one copy of replace_char() function.

tools/picture_utils.h

Index: tools/picture_utils.h
diff --git a/tools/picture_utils.h b/tools/picture_utils.h
index a5fcf7c96898cdcc178849025d2d98a4f5481639..4966bfa627df89c581d5260e22b270707d5b61cc 100644
--- a/tools/picture_utils.h
+++ b/tools/picture_utils.h
@@ -20,15 +20,6 @@ namespace sk_tools {
     // not be on the GPU.
     void force_all_opaque(const SkBitmap& bitmap);
 
-    /**
-     * Replaces all instances of oldChar with newChar in str.
-     *
-     * TODO: This function appears here and in skimage_main.cpp ;
-     * we should add the implementation to src/core/SkString.cpp, write tests for it,
-     * and remove it from elsewhere.
-     */
-    void replace_char(SkString* str, const char oldChar, const char newChar);
-
     // Returns true if the string ends with %
     bool is_percentage(const char* const string);