Check URI is valid for loading images

ImageDecoder requires URIs to have a scheme of type
SCHEME_CONTENT,
SCHEME_ANDROID_RESOURCE, or
SCHEME_FILE

In addition URI scheme being null was causing NPE since ImageDecoder
does not check for that.

Fixes: 155021174
Test: manual
Change-Id: I724c8b7e1000c2fc5b3910550ec69904da079bce