Qualify uses of std::string

PiperOrigin-RevId: 332367459
Change-Id: I8023b6ac8a3b67357dff4211d103b62b93ef8f23

tensorflow/core/platform/file_system.h

@@ -501,7 +501,7 @@ class FileSystem {
   /// \brief Get token for `path` or start a new transaction and add `path` to
   /// it.
   virtual tensorflow::Status GetTokenOrStartTransaction(
-      const string& path, TransactionToken** token) {
+      const std::string& path, TransactionToken** token) {
     *token = nullptr;
     return Status::OK();
   }

tensorflow/core/util/cuda_sparse.h

@@ -75,7 +75,8 @@ using gpuStream_t = hipStream_t;
 
 namespace tensorflow {
 
-inline string ConvertGPUSparseErrorToString(const gpusparseStatus_t status) {
+inline std::string ConvertGPUSparseErrorToString(
+    const gpusparseStatus_t status) {
   switch (status) {
 #define STRINGIZE(q) #q
 #define RETURN_IF_STATUS(err) \