[fsp] Do not allow write operations on read only file systems.

chrome/browser/chromeos/file_system_provider/operations/copy_entry.cc

Index: chrome/browser/chromeos/file_system_provider/operations/copy_entry.cc
diff --git a/chrome/browser/chromeos/file_system_provider/operations/copy_entry.cc b/chrome/browser/chromeos/file_system_provider/operations/copy_entry.cc
index 56fd67d0a43c1c00d0a3687d18657ecc88413400..a89cfc606c520fc9035008ad0617c938c576bbd5 100644
--- a/chrome/browser/chromeos/file_system_provider/operations/copy_entry.cc
+++ b/chrome/browser/chromeos/file_system_provider/operations/copy_entry.cc
@@ -28,6 +28,9 @@ CopyEntry::~CopyEntry() {
 }
 
 bool CopyEntry::Execute(int request_id) {
+  if (!file_system_info_.writable())
+    return false;
+
   scoped_ptr<base::DictionaryValue> values(new base::DictionaryValue);
   values->SetString("sourcePath", source_path_.AsUTF8Unsafe());
   values->SetString("targetPath", target_path_.AsUTF8Unsafe());