Base: Make FileProxy automaticaly close the file on a worker thread.

base/files/file_proxy.cc

Index: base/files/file_proxy.cc
diff --git a/base/files/file_proxy.cc b/base/files/file_proxy.cc
index b517761cf0cc4c0f7baae959e454ae5745f10a4c..fa04d7c44e883aaebf3eef1c068839244aae3d96 100644
--- a/base/files/file_proxy.cc
+++ b/base/files/file_proxy.cc
@@ -13,27 +13,38 @@
 #include "base/task_runner.h"
 #include "base/task_runner_util.h"
 
+namespace {
+
+void FileDeleter(base::File file) {
+}
+
+}  // namespace
+
 namespace base {
 
 class FileHelper {
  public:
    FileHelper(FileProxy* proxy, File file)
       : file_(file.Pass()),
-        proxy_(AsWeakPtr(proxy)),
-        error_(File::FILE_ERROR_FAILED) {
+        error_(File::FILE_ERROR_FAILED),
+        task_runner_(proxy->task_runner()),
+        proxy_(AsWeakPtr(proxy)) {
    }
 
    void PassFile() {
      if (proxy_)
        proxy_->SetFile(file_.Pass());
+     else if (file_.IsValid())
+       task_runner_->PostTask(FROM_HERE, Bind(&FileDeleter, Passed(&file_)));
    }
 
  protected:
   File file_;
-  WeakPtr<FileProxy> proxy_;
   File::Error error_;
 
  private:
+  scoped_refptr<TaskRunner> task_runner_;
+  WeakPtr<FileProxy> proxy_;
   DISALLOW_COPY_AND_ASSIGN(FileHelper);
 };
 
@@ -219,13 +230,12 @@ class WriteHelper : public FileHelper {
 
 }  // namespace
 
-FileProxy::FileProxy() : task_runner_(NULL) {
-}
-
 FileProxy::FileProxy(TaskRunner* task_runner) : task_runner_(task_runner) {
 }
 
 FileProxy::~FileProxy() {
+  if (file_.IsValid())
+    task_runner_->PostTask(FROM_HERE, Bind(&FileDeleter, Passed(&file_)));
 }
 
 bool FileProxy::CreateOrOpen(const FilePath& file_path,