Eliminate one copy of replace_char() function.

tools/skimage_main.cpp

Index: tools/skimage_main.cpp
diff --git a/tools/skimage_main.cpp b/tools/skimage_main.cpp
index a2d353c25de695fa5d63f96c657688227f836f44..3ed0d8de961b3db796f1d269970505ffc3dba932 100644
--- a/tools/skimage_main.cpp
+++ b/tools/skimage_main.cpp
@@ -6,6 +6,7 @@
  */
 
 #include "gm_expectations.h"
+#include "picture_utils.h"
 #include "SkBitmap.h"
 #include "SkColorPriv.h"
 #include "SkCommandLineFlags.h"
@@ -463,24 +464,6 @@ static void test_stream_without_length(const char srcPath[], SkImageDecoder* cod
 }
 #endif // defined(SK_BUILD_FOR_ANDROID) || defined(SK_BUILD_FOR_UNIX)
 
-/**
- * Replaces all instances of oldChar with newChar in str.
- *
- * TODO: This function appears here and in picture_utils.[cpp|h] ;
- * we should add the implementation to src/core/SkString.cpp, write tests for it,
- * and remove it from elsewhere.
- */
-static 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;
-        }
-    }
-}
-
 static void decodeFileAndWrite(const char srcPath[], const SkString* writePath) {
     SkBitmap bitmap;
     SkFILEStream stream(srcPath);
@@ -504,10 +487,10 @@ static void decodeFileAndWrite(const char srcPath[], const SkString* writePath)
     // Create a string representing just the filename itself, for use in json expectations.
     SkString basename = SkOSPath::Basename(srcPath);
     // Replace '_' with '-', so that the names can fit gm_json.py's IMAGE_FILENAME_PATTERN
-    replace_char(&basename, '_', '-');
+    sk_tools::replace_char(&basename, '_', '-');
     // Replace '.' with '-', so the output filename can still retain the original file extension,
     // but still end up with only one '.', which denotes the actual extension of the final file.
-    replace_char(&basename, '.', '-');
+    sk_tools::replace_char(&basename, '.', '-');
     const char* filename = basename.c_str();
 
     if (!codec->decode(&stream, &bitmap, gPrefColorType, SkImageDecoder::kDecodePixels_Mode)) {