[fsp] Buffer consecutive Write() calls.

chrome/browser/chromeos/file_system_provider/fileapi/backend_delegate.cc

Index: chrome/browser/chromeos/file_system_provider/fileapi/backend_delegate.cc
diff --git a/chrome/browser/chromeos/file_system_provider/fileapi/backend_delegate.cc b/chrome/browser/chromeos/file_system_provider/fileapi/backend_delegate.cc
index eba4927fd3a3d0b26b247205a9c132942d3db6b9..4ea467d14cc6c812a912d92f75db22cb3080621d 100644
--- a/chrome/browser/chromeos/file_system_provider/fileapi/backend_delegate.cc
+++ b/chrome/browser/chromeos/file_system_provider/fileapi/backend_delegate.cc
@@ -6,6 +6,7 @@
 
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/chromeos/file_system_provider/fileapi/buffering_file_stream_reader.h"
+#include "chrome/browser/chromeos/file_system_provider/fileapi/buffering_file_stream_writer.h"
 #include "chrome/browser/chromeos/file_system_provider/fileapi/file_stream_reader.h"
 #include "chrome/browser/chromeos/file_system_provider/fileapi/file_stream_writer.h"
 #include "chrome/browser/chromeos/file_system_provider/fileapi/provider_async_file_util.h"
@@ -24,6 +25,10 @@ namespace {
 // be read ahead of the requested data.
 const int kReaderBufferSize = 512 * 1024;  // 512KB.
 
+// Size of the stream writer internal buffer. At most this number of bytes will
+// be postponed for writing.
+const int kWriterBufferSize = 512 * 1024;  // 512KB.
+
 }  // namespace
 
 BackendDelegate::BackendDelegate()
@@ -61,8 +66,9 @@ scoped_ptr<storage::FileStreamWriter> BackendDelegate::CreateFileStreamWriter(
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DCHECK_EQ(storage::kFileSystemTypeProvided, url.type());
 
-  return scoped_ptr<storage::FileStreamWriter>(
-      new FileStreamWriter(url, offset));
+  return scoped_ptr<storage::FileStreamWriter>(new BufferingFileStreamWriter(
+      scoped_ptr<storage::FileStreamWriter>(new FileStreamWriter(url, offset)),
+      kWriterBufferSize));
 }
 
 storage::WatcherManager* BackendDelegate::GetWatcherManager(