It is not possible to add MS tile image meta via default_head_blocks.xml

[chicgeek]

It is currently not possible to add a msapplication-TileImage meta value to the head as the image path is not processed. This meta uses the content attribute instead of src or href and is used to specify the path for the tile images for Windows devices. Other similar icon paths that use src have the paths resolved correctly.

This inability to support this meta tag has been evident since before the GA release and is still an issue in 2.0.6.

Preconditions

Magento 2.0.6

Steps to reproduce

Add the following to default_head_blocks.xml. I have added other entries to this example to this show how other link / meta tags are supported, though the last line (msapplication-TileImage) is all that is required to see the broken behaviour.

<link rel="icon" type="image/png" src="images/favicons/favicon-16x16.png" sizes="16x16"/>
<link rel="manifest" src="images/favicons/default/manifest.json"/>
<meta name="theme-color" content="#00989e"/>
<meta name="msapplication-TileColor" content="#00989e"/>
<meta name="msapplication-TileImage" content="images/favicons/default/mstile-144x144.png"/>

Expected result

The content attribute for msapplication-TileImage should resolve to a localised theme path. For example:

<meta name="msapplication-TileImage" content="http://example.com/static/frontend/vendor/theme/en_GB/images/favicons/default/mstile-144x144.png">

Actual result

The content attribute for msapplication-TileImage does not resolve to a localised theme path.

<meta name="msapplication-TileImage" content="images/favicons/default/mstile-144x144.png">

[korostii]

For anyone struggling with this issue: keep in mind that, as a workaround, one can still add a block (even a simple \Magento\Framework\View\Element\Template will do the trick) into
head.additional and then inside it generate the full URL using $block->getViewFileUrl().

[magento-engcom-team]

@chicgeek, thank you for your report.
We've created internal ticket(s) MAGETWO-82524 to track progress on the issue.