Make MountPointProvider pluggable from outside webkit/fileapi

content/browser/fileapi/browser_file_system_helper.h

Index: content/browser/fileapi/browser_file_system_helper.h
diff --git a/content/browser/fileapi/browser_file_system_helper.h b/content/browser/fileapi/browser_file_system_helper.h
index 091a1f287fdfd7712c01ea3ad72724f350729db6..53c01cadd72cef3a5c09424b25d71076da3e7df7 100644
--- a/content/browser/fileapi/browser_file_system_helper.h
+++ b/content/browser/fileapi/browser_file_system_helper.h
@@ -23,9 +23,15 @@ namespace content {
 
 // Helper method that returns FileSystemContext constructed for
 // the browser process.
+//
+// |external_mount_points| contains non-system external mount points available
+// in the context. If not NULL, it will be used during URL cracking. On
+// ChromeOS, it will be passed to external_mount_point_provider.
+// |external_mount_points| may be NULL only on platforms different from
+// ChromeOS (i.e. platforms that don't use external_mount_point_provider).
 CONTENT_EXPORT scoped_refptr<fileapi::FileSystemContext>
 CreateFileSystemContext(
-    const base::FilePath& profile_path,
+    const base::FilePath& partition_path,
     bool is_incognito,
     fileapi::ExternalMountPoints* external_mount_points,
     quota::SpecialStoragePolicy* special_storage_policy,