Revert "Delete rtc::Pathname"

This reverts commit 6b9dec0d16f2df59fa2820c5ec1341be52fb9f32.

Reason for revert: speculative revert for breaking internal projects

Original change's description:
> Delete rtc::Pathname
> 
> Bug: webrtc:6424
> Change-Id: Iec01dc5dd1426d4558983b828b67af872107d723
> Reviewed-on: https://webrtc-review.googlesource.com/c/108400
> Commit-Queue: Niels Moller <nisse@webrtc.org>
> Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#25479}

TBR=kwiberg@webrtc.org,nisse@webrtc.org

Change-Id: I3129a81a1d8e36b3e6c67572410bdc478ec4d5e9
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:6424
Reviewed-on: https://webrtc-review.googlesource.com/c/109201
Reviewed-by: Qingsi Wang <qingsi@webrtc.org>
Commit-Queue: Qingsi Wang <qingsi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25490}
diff --git a/rtc_base/fileutils.h b/rtc_base/fileutils.h
index d85b6b1..deaf2e3 100644
--- a/rtc_base/fileutils.h
+++ b/rtc_base/fileutils.h
@@ -25,6 +25,8 @@
 
 namespace rtc {
 
+class Pathname;
+
 //////////////////////////
 // Directory Iterator   //
 //////////////////////////
@@ -42,25 +44,22 @@
   // Destructor
   virtual ~DirectoryIterator();
 
-  // Starts traversing a directory.
-  // |dir| is the directory to traverse.
-  // returns true if the directory exists and is valid.
-  // The iterator will point to the first entry in the directory.
-  virtual bool Iterate(const std::string& dir);
+  // Starts traversing a directory
+  // dir is the directory to traverse
+  // returns true if the directory exists and is valid
+  // The iterator will point to the first entry in the directory
+  virtual bool Iterate(const Pathname& path);
 
   // Advances to the next file
   // returns true if there were more files in the directory.
   virtual bool Next();
 
-  // Returns true if the file currently pointed to is a directory.
+  // returns true if the file currently pointed to is a directory
   virtual bool IsDirectory() const;
 
-  // Returns the name of the file currently pointed to.
+  // returns the name of the file currently pointed to
   virtual std::string Name() const;
 
-  // Returns complete name of the file, including directory part.
-  virtual std::string PathName() const;
-
  private:
   std::string directory_;
 #if defined(WEBRTC_WIN)
@@ -80,37 +79,42 @@
   // This will attempt to delete the path located at filename.
   // It DCHECKs and returns false if the path points to a folder or a
   // non-existent file.
-  virtual bool DeleteFile(const std::string& filename) = 0;
+  virtual bool DeleteFile(const Pathname& filename) = 0;
 
   // This moves a file from old_path to new_path, where "old_path" is a
   // plain file. This DCHECKs and returns false if old_path points to a
   // directory, and returns true if the function succeeds.
-  virtual bool MoveFile(const std::string& old_path,
-                        const std::string& new_path) = 0;
+  virtual bool MoveFile(const Pathname& old_path, const Pathname& new_path) = 0;
+
+  // Returns true if pathname refers to a directory
+  virtual bool IsFolder(const Pathname& pathname) = 0;
 
   // Returns true if pathname refers to a file
-  virtual bool IsFile(const std::string& pathname) = 0;
+  virtual bool IsFile(const Pathname& pathname) = 0;
 
   // Determines the size of the file indicated by path.
-  virtual bool GetFileSize(const std::string& path, size_t* size) = 0;
+  virtual bool GetFileSize(const Pathname& path, size_t* size) = 0;
 };
 
 class Filesystem {
  public:
-  static bool DeleteFile(const std::string& filename) {
+  static bool DeleteFile(const Pathname& filename) {
     return GetFilesystem()->DeleteFile(filename);
   }
 
-  static bool MoveFile(const std::string& old_path,
-                       const std::string& new_path) {
+  static bool MoveFile(const Pathname& old_path, const Pathname& new_path) {
     return GetFilesystem()->MoveFile(old_path, new_path);
   }
 
-  static bool IsFile(const std::string& pathname) {
+  static bool IsFolder(const Pathname& pathname) {
+    return GetFilesystem()->IsFolder(pathname);
+  }
+
+  static bool IsFile(const Pathname& pathname) {
     return GetFilesystem()->IsFile(pathname);
   }
 
-  static bool GetFileSize(const std::string& path, size_t* size) {
+  static bool GetFileSize(const Pathname& path, size_t* size) {
     return GetFilesystem()->GetFileSize(path, size);
   }