Chrome version: 70.0.3538.67 and 71.0.3578.30.
OS version: Windows 10
Case#: 17239892

Description: "Mailto:" hyperlinks don't work after Chrome browser was updated to 70. Continues on 71.
- Gmail is the default mail handler on Chrome settings.
- It's affecting multiple users on multiple Windows 10 machines.

Current Behavior / Reproduction: 
1. Go to https://sites.google.com/a/test.gpartner.eu/testo/home.
2. Click on mailto: link.
3. A new tab is opened but it's blank. No email service is opened.

Expected Behavior: 
A new tab or window opens with default email handler.

Drive link to logs: https://drive.google.com/corp/drive/folders/1lMek2PuUiPFDlQ0WjlxWkH1eILIBdtJt

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The following steps worked for customer once on 70 but it's not working anymore on Chrome 71 and other users are also affected:

1. Go to chrome://settings/handlers 
2. Switch the only setting to OFF and then to ON. 
3. Open Gmail in a different tab. 
4. At the upper right corner, to the left of the bookmarks icon, you can see the Handler icon; click on it. 
5. Click on Allow, then on Done. This will open the Windows Default apps window. You may close it. 
6. Go back to the test website, refresh it, and click on the mailto link. Gmail should open on a new tab as expected.