mojo filesystem: Simplify full file reading/writing.

components/filesystem/file_impl.cc

Index: components/filesystem/file_impl.cc
diff --git a/components/filesystem/file_impl.cc b/components/filesystem/file_impl.cc
index da156c8618c7a3e0c5e378d8cf554dedec12e11f..8a3682b075e0c20bb1bc26b5edb4054be7b95877 100644
--- a/components/filesystem/file_impl.cc
+++ b/components/filesystem/file_impl.cc
@@ -94,28 +94,6 @@ void FileImpl::Read(uint32_t num_bytes_to_read,
   callback.Run(FileError::OK, std::move(bytes_read));
 }
 
-void FileImpl::ReadEntireFile(const ReadEntireFileCallback& callback) {
-  if (!file_.IsValid()) {
-    callback.Run(GetError(file_), mojo::Array<uint8_t>());
-    return;
-  }
-
-  // Seek to the front of the file.
-  if (file_.Seek(base::File::FROM_BEGIN, 0) == -1) {
-    callback.Run(FileError::FAILED, mojo::Array<uint8_t>());
-    return;
-  }
-
-  std::string contents;
-  const int kBufferSize = 1 << 16;
-  scoped_ptr<char[]> buf(new char[kBufferSize]);
-  size_t len;
-  while ((len = file_.ReadAtCurrentPos(buf.get(), kBufferSize)) > 0)
-    contents.append(buf.get(), len);
-
-  callback.Run(FileError::OK, mojo::Array<uint8_t>::From(contents));
-}
-
 // TODO(vtl): Move the implementation to a thread pool.
 void FileImpl::Write(mojo::Array<uint8_t> bytes_to_write,
                      int64_t offset,