Steps to reproduce the problem:
I am an iOS developer. In our app action extension we are trying to modify the webpage contents in browser (chrome). This can be accomplished in Safari via javascript file provided in NSExtensionJavaScriptPreprocessingFile (plist). I can understand that chrome will not have access to that javascript file. Any other mechanism, to replace the same is expected. In chrome, webpage URL and title are only provided as inputs to extension. 
 Steps :
1.  Have any app extension that modifies the web page content via  NSExtensionJavaScriptPreprocessingFile, following the mechanism proposed by Apple for Safari
2. In chrome app's Activity view controller , trigger the above mentioned app action extension.
3. Webpage is not modified. (Javascript file is ignored)

What is the expected behavior?
Chrome should also have an option via action extension to modify the webpage contents. Safari like mechanism using NSExtensionJavaScriptPreprocessingFile javascript file cannot be accomplished in chrome. 
This can accomplished by the following mechanism ( which I could think of)
 Chrome can provide the webpage contents via action extension inputs to activities. The extension can generate the javascript to modify the webpage content and provide it to chrome(host application) to inject the same on the webpage.
Any other solution to solve the same would be fine.

What went wrong?
Safari's feature is missed out here. Chrome users not restricted from app extensions which modifies the webpage.

Did this work before? No 

Chrome version: 52.0.2743.84  Channel: stable
OS Version: iOS 9
Flash Version: Shockwave Flash 22.0 r0