Docserver: Use GitilesFileSystem instead of SubversionFileSystem

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

Index: chrome/common/extensions/docs/server2/caching_file_system.py
diff --git a/chrome/common/extensions/docs/server2/caching_file_system.py b/chrome/common/extensions/docs/server2/caching_file_system.py
index ecadb68ab5d4ee6938ff51e64da4e69c4ef1e37c..b5434581f595f136ea9ffaf881d6a537d0ad3036 100644
--- a/chrome/common/extensions/docs/server2/caching_file_system.py
+++ b/chrome/common/extensions/docs/server2/caching_file_system.py
@@ -124,6 +124,12 @@ class CachingFileSystem(FileSystem):
     return self._file_system.Read(set(paths) - set(fresh_data.iterkeys()),
                                   skip_not_found=skip_not_found).Then(next)
 
+  def GetCommitID(self):
+    return self._file_system.GetCommitID()
+
+  def GetPreviousCommitID(self):
+    return self._file_system.GetPreviousCommitID()
+
   def GetIdentity(self):
     return self._file_system.GetIdentity()