GN: Move towards only using / on Windows

base/files/file_path.cc

Index: base/files/file_path.cc
diff --git a/base/files/file_path.cc b/base/files/file_path.cc
index d47becbacca30815ca1284a3aad2a2d229be16cd..37bcd4c8bec9899a67219b6dc8dd045ec3a80b0a 100644
--- a/base/files/file_path.cc
+++ b/base/files/file_path.cc
@@ -1292,10 +1292,14 @@ void FilePath::StripTrailingSeparatorsInternal() {
 }
 
 FilePath FilePath::NormalizePathSeparators() const {
+  return NormalizePathSeparatorsTo(kSeparators[0]);
+}
+
+FilePath FilePath::NormalizePathSeparatorsTo(CharType separator) const {
 #if defined(FILE_PATH_USES_WIN_SEPARATORS)
   StringType copy = path_;
-  for (size_t i = 1; i < kSeparatorsLength; ++i) {
-    std::replace(copy.begin(), copy.end(), kSeparators[i], kSeparators[0]);
+  for (size_t i = 0; i < kSeparatorsLength; ++i) {
+    std::replace(copy.begin(), copy.end(), kSeparators[i], separator);
   }
   return FilePath(copy);
 #else