Remove thread restriction of fileapi::FileSystemContext::ResolveURL.

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 f6e7df3a2d6d532075a406f9c61f4b7c8ecd2b4a..4631b79b8a7558b4dcadc8a643c152a952a4269e 100644
--- a/webkit/browser/fileapi/file_system_context.cc
+++ b/webkit/browser/fileapi/file_system_context.cc
@@ -57,6 +57,18 @@ void DidGetMetadataForResolveURL(
   callback.Run(error, info, path, file_info.is_directory);
 }
 
+void RelayResolveURLCallback(
+    scoped_refptr<base::MessageLoopProxy> message_loop,
+    const FileSystemContext::ResolveURLCallback& callback,
+    base::File::Error result,
+    const FileSystemInfo& info,
+    const base::FilePath& file_path,
+    bool is_directory) {
+  message_loop->PostTask(
+      FROM_HERE,
+      base::Bind(callback, result, info, file_path, is_directory));
+}
+
 }  // namespace
 
 // static
@@ -322,11 +334,19 @@ void FileSystemContext::OpenFileSystem(
 void FileSystemContext::ResolveURL(
     const FileSystemURL& url,
     const ResolveURLCallback& callback) {
-  // TODO(nhiroki, kinuko): Remove this thread restriction, so it can be called
-  // on either UI or IO thread.
-  DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
   DCHECK(!callback.is_null());
 
+  // If not on IO thread, forward before passing the task to the backend.
+  if (!io_task_runner_->RunsTasksOnCurrentThread()) {
+    ResolveURLCallback relay_callback =
+        base::Bind(&RelayResolveURLCallback,
+                   base::MessageLoopProxy::current(), callback);
+    io_task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(&FileSystemContext::ResolveURL, this, url, relay_callback));
+    return;
+  }
+
   FileSystemBackend* backend = GetFileSystemBackend(url.type());
   if (!backend) {
     callback.Run(base::File::FILE_ERROR_SECURITY,