[fsp] Add FileStreamReader for the reading operation.

chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_apitest.cc

Index: chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_apitest.cc
diff --git a/chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_apitest.cc b/chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_apitest.cc
index db78129390a47322388480934e1d0c7da6913349..1cf3ea83dc07a83c79b7c55a5eccc05152ef405a 100644
--- a/chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_apitest.cc
+++ b/chrome/browser/chromeos/extensions/file_system_provider/file_system_provider_apitest.cc
@@ -41,4 +41,10 @@ IN_PROC_BROWSER_TEST_F(FileSystemProviderApiTest, ReadDirectory) {
       << message_;
 }
 
+IN_PROC_BROWSER_TEST_F(FileSystemProviderApiTest, ReadFile) {
+  ASSERT_TRUE(RunPlatformAppTestWithFlags("file_system_provider/read_file",
+                                          kFlagLoadAsComponent))
+      << message_;
+}
+
 }  // namespace extensions