Add mechanism to auto mount file systems in response to a URL request.

content/public/test/test_file_system_backend.cc

Index: content/public/test/test_file_system_backend.cc
diff --git a/content/public/test/test_file_system_backend.cc b/content/public/test/test_file_system_backend.cc
index b473716cd8617dbc09d32b3ad17713a4fb44873a..8c37a9e525597de50b138525da269c82a50ff50b 100644
--- a/content/public/test/test_file_system_backend.cc
+++ b/content/public/test/test_file_system_backend.cc
@@ -137,7 +137,6 @@ class TestFileSystemBackend::QuotaUtil
 
   virtual const fileapi::AccessObserverList* GetAccessObservers(
       FileSystemType type) const OVERRIDE {
-    NOTIMPLEMENTED();
     return NULL;
   }