Remove some PlatformFile instances from ChromeOS Drive.

net/base/file_stream_context.cc

Index: net/base/file_stream_context.cc
diff --git a/net/base/file_stream_context.cc b/net/base/file_stream_context.cc
index 43825e3109452b62a343ac17ce04f5067377ea8a..5d1fdbb013054412bbd03fb94d262ea2dd4d3712 100644
--- a/net/base/file_stream_context.cc
+++ b/net/base/file_stream_context.cc
@@ -274,21 +274,16 @@ void FileStream::Context::CloseAndDelete() {
   DCHECK(!async_in_progress_);
 
   if (file_.IsValid()) {
-    bool posted = task_runner_.get()->PostTaskAndReply(
+    bool posted = task_runner_.get()->PostTask(
         FROM_HERE,
         base::Bind(base::IgnoreResult(&Context::CloseFileImpl),
-                   base::Unretained(this)),
-        base::Bind(&Context::OnCloseCompleted, base::Unretained(this)));
+                   base::Owned(this)));
     DCHECK(posted);
   } else {
     delete this;
   }
 }
 
-void FileStream::Context::OnCloseCompleted() {
-  delete this;
-}
-
 Int64CompletionCallback FileStream::Context::IntToInt64(
     const CompletionCallback& callback) {
   return base::Bind(&CallInt64ToInt, callback);