[fsp] Improve performance for reading small chunks of data.

chrome/browser/chromeos/fileapi/file_system_backend.cc

Index: chrome/browser/chromeos/fileapi/file_system_backend.cc
diff --git a/chrome/browser/chromeos/fileapi/file_system_backend.cc b/chrome/browser/chromeos/fileapi/file_system_backend.cc
index e65417808448733d7092abf0067415b1d45a3c4b..440aefe3576cf418cfd27c8f4b31fea46383542f 100644
--- a/chrome/browser/chromeos/fileapi/file_system_backend.cc
+++ b/chrome/browser/chromeos/fileapi/file_system_backend.cc
@@ -311,6 +311,7 @@ scoped_ptr<webkit_blob::FileStreamReader>
 FileSystemBackend::CreateFileStreamReader(
     const fileapi::FileSystemURL& url,
     int64 offset,
+    int64 length,
     const base::Time& expected_modification_time,
     fileapi::FileSystemContext* context) const {
   DCHECK(url.is_valid());
@@ -321,10 +322,10 @@ FileSystemBackend::CreateFileStreamReader(
   switch (url.type()) {
     case fileapi::kFileSystemTypeDrive:
       return drive_delegate_->CreateFileStreamReader(
-          url, offset, expected_modification_time, context);
+          url, offset, length, expected_modification_time, context);
     case fileapi::kFileSystemTypeProvided:
       return file_system_provider_delegate_->CreateFileStreamReader(
-          url, offset, expected_modification_time, context);
+          url, offset, length, expected_modification_time, context);
     case fileapi::kFileSystemTypeNativeLocal:
     case fileapi::kFileSystemTypeRestrictedNativeLocal:
       return scoped_ptr<webkit_blob::FileStreamReader>(
@@ -332,7 +333,7 @@ FileSystemBackend::CreateFileStreamReader(
               context, url, offset, expected_modification_time));
     case fileapi::kFileSystemTypeDeviceMediaAsFileStorage:
       return mtp_delegate_->CreateFileStreamReader(
-          url, offset, expected_modification_time, context);
+          url, offset, length, expected_modification_time, context);
     default:
       NOTREACHED();
   }