base: Remove deprecated file_util::GetFilenameFromPath function.

base/file_util.cc

Index: base/file_util.cc
diff --git a/base/file_util.cc b/base/file_util.cc
index 2b5dc84df24daa5cb1ee246430f808ad2c983d0f..d1a46c92fbca89651dfe244462289c28cc3dc5c8 100644
--- a/base/file_util.cc
+++ b/base/file_util.cc
@@ -386,12 +386,6 @@ std::wstring GetFileExtensionFromPath(const std::wstring& path) {
       GetFileExtensionFromPath(FilePath::FromWStringHack(path));
   return extension;
 }
-std::wstring GetFilenameFromPath(const std::wstring& path) {
-  if (path.empty() || EndsWithSeparator(FilePath::FromWStringHack(path)))
-    return std::wstring();
-
-  return FilePath::FromWStringHack(path).BaseName().ToWStringHack();
-}
 FILE* OpenFile(const std::wstring& filename, const char* mode) {
   return OpenFile(FilePath::FromWStringHack(filename), mode);
 }