WebEditor: base implementation

app/controllers/tree_controller.rb

@@ -26,8 +26,14 @@ class TreeController < ProjectResourceController
 
   def update
     file_editor = Gitlab::FileEditor.new(current_user, @project, @ref)
-    if file_editor.can_edit?(@path, params[:last_commit])
-      file_editor.update(@path, params[:content])
+    update_status = file_editor.update(
+      @path, 
+      params[:content], 
+      params[:commit_message], 
+      params[:last_commit]
+    )
+    
+    if update_status
       redirect_to project_tree_path(@project, @id), :notice => "File has been successfully changed"
     else
       flash[:notice] = "You can't save file because it has been changed"