Themes: Get resources with an explicit theme attached.

Change-Id: If04e82a13250f520d70b58991586c8ce38f0ecb1
Don't log an error if we cannot open icon hash

The icons will end up being processed if we cannot access the hash
so let's just fail gracefully and silently.

Change-Id: I6368ee9bb47a9d52351fff22283ffac2de625b71