Assigning to Mihai to take a look. Mihai, feel free to re-assign if this isn't actually an issue with signin/the chrome.identity API.

This seems like a very ugly bug for folks that are using the Chrome Identity API. We should probably tackle it before he next release.

I have a CL out. Not sure if this will get landed before branch point though.

We can always merge.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a8f5066a367be8011a77a7be6a32853d3448ec06

commit a8f5066a367be8011a77a7be6a32853d3448ec06
Author: msarda <msarda@chromium.org>
Date: Wed May 31 13:26:32 2017

Avoid treating the load of about:blank as a failure in the web auth flow.

As part of the OAUth 2.0 protocol with GAIA, at the end of the web
authorization flow, GAIA redirects to a custom scheme URL of type
|com.googleusercontent.apps.123:/<extension_id>|, where
|com.googleusercontent.apps.123| is the reverse DNS notation of the
client ID.

It look like this URL is not an web accessible URL from within a Guest WebView, so
during the load of this URL, Chrome validates and changes it to "about:blank",
which then fails to be loaded within the context of the Identity Scope Approval
Dialog extension. Note that in fact, it is better to avoid the load of |about:blank|
as the dialog will actually be closed right after this load fails.

This CL avoids treating the failure of loading |about:blank| as a failure
of the web auth flow.

BUG= 722323 

Review-Url: https://codereview.chromium.org/2901283002
Cr-Commit-Position: refs/heads/master@{#475894}

[modify] https://crrev.com/a8f5066a367be8011a77a7be6a32853d3448ec06/chrome/browser/extensions/api/identity/web_auth_flow.cc

Your change meets the bar and is auto-approved for M60. Please go ahead and merge the CL to branch 3112 manually. Please contact milestone owner if you have questions.
Owners: amineer@(Android), cmasso@(iOS), josafat@(ChromeOS), bustamante@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Thanks for the fix. 

Please confirm whether the fix is verified in canary. If yes, merge to 3112 branch ASAP.

Tested on Windows Canary.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/443ffe5729635a7e0e2313278393443c7611af66

commit 443ffe5729635a7e0e2313278393443c7611af66
Author: Mihai Sardarescu <msarda@chromium.org>
Date: Fri Jun 02 15:29:11 2017

Avoid treating the load of about:blank as a failure in the web auth flow.

As part of the OAUth 2.0 protocol with GAIA, at the end of the web
authorization flow, GAIA redirects to a custom scheme URL of type
|com.googleusercontent.apps.123:/<extension_id>|, where
|com.googleusercontent.apps.123| is the reverse DNS notation of the
client ID.

It look like this URL is not an web accessible URL from within a Guest WebView, so
during the load of this URL, Chrome validates and changes it to "about:blank",
which then fails to be loaded within the context of the Identity Scope Approval
Dialog extension. Note that in fact, it is better to avoid the load of |about:blank|
as the dialog will actually be closed right after this load fails.

This CL avoids treating the failure of loading |about:blank| as a failure
of the web auth flow.

BUG= 722323 

Review-Url: https://codereview.chromium.org/2901283002
Cr-Original-Commit-Position: refs/heads/master@{#475894}
Review-Url: https://codereview.chromium.org/2919943003 .
Cr-Commit-Position: refs/branch-heads/3112@{#116}
Cr-Branched-From: b6460e24cf59f429d69de255538d0fc7a425ccf9-refs/heads/master@{#474897}

[modify] https://crrev.com/443ffe5729635a7e0e2313278393443c7611af66/chrome/browser/extensions/api/identity/web_auth_flow.cc

Tested the issue on windows 7 using chrome M60 #60.0.3112.20 and followed below steps:

 - Removed "Chrome Remote Desktop" Permission from My connected apps https://myaccount.google.com/permissions
 - Opened Chrome identity internal chrome://identity-internals and observed
 - Now re launched Chrome Remote Desktop App again
 - observed that there is a prompt for Google Authorisation and signed into chrome and chrome remote desktop launched
 

Attached screencast for reference.

@Could someone check attached screencast and confirm us if this is the expected result or if we had missed any steps in verifying the issue.

Thanks!

Deleted: 722323.mp4 5.9 MB

	722323.mp4 5.9 MB View Download

Correct Test Scenarios
 
To verify this fix,
Method 1) Use email Id that has never used "chrome remote desktop" or use newly created email id 

Method 2) 
 -1 Remove "Chrome Remote Desktop" Permission from My connected apps https://myaccount.google.com/permissions ( if one has installed.
 -2 Open Chrome identity internal chrome://identity-internals and observe
 -3 Now re launch Chrome Remote Desktop App again
 -4 You will see that it won't prompt for Google Authorization
 -5 We have to manually remove from chrome://identity-internals
 -6 Now if u reopen Chrome Remote Desktop App you will see this error
5th important step missed.
BTW, I tested using 2) method. Please verify using 1st) method, use newly created email id.one

 Issue 727320  has been merged into this issue.