Get rid of the deprecated file_util::InsertBeforeExtension.

base/file_util_deprecated.h

Index: base/file_util_deprecated.h
diff --git a/base/file_util_deprecated.h b/base/file_util_deprecated.h
index 148c023206870cd0f24b0a370491e9b0e6f480fd..70857ef094b1453f8e7ee85cf75440768cedfddd 100644
--- a/base/file_util_deprecated.h
+++ b/base/file_util_deprecated.h
@@ -51,9 +51,6 @@ std::wstring GetFileExtensionFromPath(const std::wstring& path);
 
 bool AbsolutePath(std::wstring* path);
 
-// Use FilePath::InsertBeforeExtension.
-void InsertBeforeExtension(FilePath* path, const FilePath::StringType& suffix);
-
 // Use version that takes a FilePath.
 bool Delete(const std::wstring& path, bool recursive);
 bool CopyDirectory(const std::wstring& from_path, const std::wstring& to_path,