Use OnBufferVisit in ultisnips completer

This is instead of OnFileReadyToParse which is called every time the users stops
typing.

autoload/youcompleteme.vim

@@ -205,6 +205,7 @@ function! s:OnBufferVisit()
 
   call s:SetUpCompleteopt()
   call s:SetCompleteFunc()
+  py ycm_state.OnBufferVisit()
   call s:OnFileReadyToParse()
 endfunction
 

python/completers/general/ultisnips_completer.py

@@ -50,7 +50,7 @@ class UltiSnipsCompleter( GeneralCompleter ):
     return self._filtered_candidates if self._filtered_candidates else []
 
 
-  def OnFileReadyToParse( self ):
+  def OnBufferVisit( self ):
     self._candidates = _GetCandidates()
 
 

python/ycm.py

@@ -145,6 +145,13 @@ class YouCompleteMe( object ):
       self.GetFiletypeCompleter().OnBufferDelete( deleted_buffer_file )
 
 
+  def OnBufferVisit( self ):
+    self.gencomp.OnBufferVisit()
+
+    if self.FiletypeCompletionUsable():
+      self.GetFiletypeCompleter().OnBufferVisit()
+
+
   def OnInsertLeave( self ):
     self.gencomp.OnInsertLeave()