[FileAPI] Remove Flush() on write completion on SandboxFileSystems

webkit/browser/fileapi/file_system_context.cc

Index: webkit/browser/fileapi/file_system_context.cc
diff --git a/webkit/browser/fileapi/file_system_context.cc b/webkit/browser/fileapi/file_system_context.cc
index 549293959aac5d891256b30ea686913989e7b98c..0df0a1dfced0ce0301d6cd098540311e0f717675 100644
--- a/webkit/browser/fileapi/file_system_context.cc
+++ b/webkit/browser/fileapi/file_system_context.cc
@@ -479,6 +479,20 @@ bool FileSystemContext::CanServeURLRequest(const FileSystemURL& url) const {
   return !is_incognito_ || !FileSystemContext::IsSandboxFileSystem(url.type());
 }
 
+bool FileSystemContext::ShouldFlushOnWriteCompletion(
+    FileSystemType type) const {
+  if (IsSandboxFileSystem(type)) {
+    // Disable Flush() for each write operation on SandboxFileSystems since it
+    // hurts the performance, assuming the FileSystems are stored in a local
+    // disk, we don't need to keep calling fsync() for it.
+    // On the other hand, other FileSystems that may stored on a removable media
+    // should be Flush()ed as soon as a write operation is completed, so that
+    // written data is saved over sudden media removal.
+    return false;
+  }
+  return true;
+}
+
 void FileSystemContext::OpenPluginPrivateFileSystem(
     const GURL& origin_url,
     FileSystemType type,