UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.112 Safari/537.36

Steps to reproduce the problem:
1. set up network abort, I used fiddler to reproduce with the custom rule. this looks the same to the client as an aborted connection. note if using fiddler, you'll have to also set fiddler to capture/decrypt https with the generated trusted root cert, etc (note this happens in non-dev envs just to give you easy steps).  
```
    public static RulesOption("Stuck in Connecting")
    BindPref("fiddlerscript.rules.StuckConnecting")
    var m_StuckConnecting: boolean = false;

...
    static function OnBeforeRequest(oSession: Session) {
...
	if (m_StuckConnecting) {
            if (oSession.fullUrl.IndexOf("https://clients2.googleusercontent.com") !== -1) {
               oSession.utilCreateResponseAndBypassServer();
               oSession.responseCode = 0;  
               oSession.oResponse.headers.HTTPResponseCode = 0;
               oSession.oResponse.headers.HTTPResponseStatus = "0 Client Connection Dropped by script";
               oSession.state = SessionStates.Aborted;
           }
        }
```
2. Go to chrome extension page
3. Turn on rule/ensure that the connection to https://clients2.googleusercontent.com will abort
4. Click Add to Chrome
5. See how it is stuck in "Checking" and doesn't report the error (bug 1)
6. Turn off fiddler rule (allow connections to clients2.googleusercontent.com)
7. Refresh the page to try and reset the scenario
8. Click Add to Chrome
9. See error message "An error has occurred
This item is already being downloaded and added into Chrome.
RELOADCLOSE
" ( bug 2 )

What is the expected behavior?
bug 1: when connection is aborted, I would expect an error message and to be forced to try the process again.
 bug 2 : i would expect a page refresh to reset the state assuming 1 is just a bug in the web page, but I can see that this might be a bug in the state machine internal to the browser. 

Currently, you can install again if you totally quit the browser.

What went wrong?
We originally got the report from one of our chromebook schools during an onsite visit. They were going around and installing on all machines in the classroom and were getting stuck on the "Checking" step on about 6 out of 20 machines. We then brought this back into our lab to isolate the cause (hence the fiddler rule).

The high level is that if the connection to clients2.googleusercontent.com gets aborted, you won't be able to install the extension as even a page refresh doesn't resolve it. Totally quitting the browser does seem to reset the state.

WebStore page: 

Did this work before? N/A 

Chrome version: 49.0.2623.112  Channel: stable
OS Version: 10.0
Flash Version: Shockwave Flash 21.0 r0

(sorry if this double posted, there wasnt a confirmation and I couldn't find it in crbug after submission