Docserver: Persist stat cache for versioned file systems

chrome/common/extensions/docs/server2/mock_file_system.py

Index: chrome/common/extensions/docs/server2/mock_file_system.py
diff --git a/chrome/common/extensions/docs/server2/mock_file_system.py b/chrome/common/extensions/docs/server2/mock_file_system.py
index 76942f809da1f83599927a8383dcae6096bc4795..1484ab1728175316f826facee555dbdc28df7c08 100644
--- a/chrome/common/extensions/docs/server2/mock_file_system.py
+++ b/chrome/common/extensions/docs/server2/mock_file_system.py
@@ -25,6 +25,7 @@ class MockFileSystem(FileSystem):
     self._read_count = 0
     self._read_resolve_count = 0
     self._stat_count = 0
+    self._version = None
 
   @staticmethod
   def Create(file_system, updates):
@@ -86,14 +87,17 @@ class MockFileSystem(FileSystem):
     return stat
 
   def GetCommitID(self):
-    return Future(value=self._stat_tracker.GetVersion(''))
+    return Future(value=str(self._stat_tracker.GetVersion('')))
 
   def GetPreviousCommitID(self):
-    return Future(value=self._stat_tracker.GetVersion('') - 1)
+    return Future(value=str(self._stat_tracker.GetVersion('') - 1))
 
   def GetIdentity(self):
     return self._file_system.GetIdentity()
 
+  def GetVersion(self):
+    return self._version
+
   def __str__(self):
     return repr(self)
 
@@ -136,3 +140,7 @@ class MockFileSystem(FileSystem):
       # derived from |_updates|.
       if not IsDirectory(path):
         self._stat_tracker.SetVersion(path, len(self._updates))
+
+  def SetVersion(self, version):
+    '''Override the reported FileSystem version (default None) for testing.'''
+    self._version = version