Revert of mojo filesystem: Simplify full file reading/writing.

components/filesystem/directory_impl.h

Index: components/filesystem/directory_impl.h
diff --git a/components/filesystem/directory_impl.h b/components/filesystem/directory_impl.h
index 4f5b1a4ddd5e0a9f12460d34325d9077a134f5ed..1e4c903443ea3ef564d687639fd99802c50adb2e 100644
--- a/components/filesystem/directory_impl.h
+++ b/components/filesystem/directory_impl.h
@@ -55,11 +55,6 @@
   void IsWritable(const mojo::String& path,
                   const IsWritableCallback& callback) override;
   void Flush(const FlushCallback& callback) override;
-  void ReadEntireFile(const mojo::String& path,
-                      const ReadEntireFileCallback& callback) override;
-  void WriteFile(const mojo::String& path,
-                 mojo::Array<uint8_t> data,
-                 const WriteFileCallback& callback) override;
 
  private:
   mojo::StrongBinding<Directory> binding_;