Chrome Version       : 59.0.3071.115
OS Version: 10.0
URLs (if applicable) : -
Other browsers tested:
Firefox 52 64 Bit (The problem does not occur here)

What steps will reproduce the problem?
1. Create a chrome extension with native messaging and message passing from content script to background script and native messaging host
   - content script: window.addEventListener / chrome.runtime.connect / chrome.runtime.postMessage
   - background script: chrome.runtime.onConnect.addListener / Port.onMessage.addListener / chrome.runtime.connectNative / Port.postMessage

2. Send a big amount of JSON objects (e.g. some hundred) with big strings contained (about 1 MB each) over the native messaging mechanism to the native messaging host

What is the expected result?
Memory consumption of the extension process (Contains "--extension-process" on the command line shown in Windows task manager) does not grow up.


What happens instead of that?
Each serialized string of the data JSON object beeing sent is leaked in the extension process and the memory consumption grows up rapidly and does not go down any more when no more data is sent.

When analyzing memory in F12/Memory in "Summary" I can see that JS memory consumption keeps low (the big data objects keep nowhere referenced, the sum of "Shallow Size" objects keeps constantly low), but when looking at the "Containment" section, every single big data objects is shown in the "(Global handles)" area as a single serialized string.
Nowhere in the extension code the data beeing transferred is serialized in our code.
According to the docs "(Global handles)" means objects from VM heap that are temporarily referenced from the currently running native code.
The "Summary" section looks like:
Code: 820 KB, Strings: 313 KB, JS Arrays: 23 KB, Typed Arrays: 0 KB, System Objects: 168301 KB, Total: 171044 KB.


When running the exact same scenario with exactly the same extension code in Firefox, the data are not leaked (The sum of memory consumption of all Firefox processes shown in Windows task manager keeps nearly constant and does not explode).

UserAgentString: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/59.0.3071.115 Safari/537.36