[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 ae2947d9771f4867361f311052f4a6e82dd65369..6afd01add9acb684e6e0d6878ba2cca05d3321d9 100644
--- a/chrome/browser/chromeos/fileapi/file_system_backend.cc
+++ b/chrome/browser/chromeos/fileapi/file_system_backend.cc
@@ -314,6 +314,7 @@ bool FileSystemBackend::HasInplaceCopyImplementation(
 scoped_ptr<storage::FileStreamReader> FileSystemBackend::CreateFileStreamReader(
     const storage::FileSystemURL& url,
     int64 offset,
+    int64 length,
     const base::Time& expected_modification_time,
     storage::FileSystemContext* context) const {
   DCHECK(url.is_valid());
@@ -324,10 +325,10 @@ scoped_ptr<storage::FileStreamReader> FileSystemBackend::CreateFileStreamReader(
   switch (url.type()) {
     case storage::kFileSystemTypeDrive:
       return drive_delegate_->CreateFileStreamReader(
-          url, offset, expected_modification_time, context);
+          url, offset, length, expected_modification_time, context);
     case storage::kFileSystemTypeProvided:
       return file_system_provider_delegate_->CreateFileStreamReader(
-          url, offset, expected_modification_time, context);
+          url, offset, length, expected_modification_time, context);
     case storage::kFileSystemTypeNativeLocal:
     case storage::kFileSystemTypeRestrictedNativeLocal:
       return scoped_ptr<storage::FileStreamReader>(
@@ -335,7 +336,7 @@ scoped_ptr<storage::FileStreamReader> FileSystemBackend::CreateFileStreamReader(
               context, url, offset, expected_modification_time));
     case storage::kFileSystemTypeDeviceMediaAsFileStorage:
       return mtp_delegate_->CreateFileStreamReader(
-          url, offset, expected_modification_time, context);
+          url, offset, length, expected_modification_time, context);
     default:
       NOTREACHED();
   }