To determine mime-types of attachments from the ACTION_SEND and _MULTIPLE intents,
- Use ContentResolver.getType() for content: URIs
- Use inferMimeType() for file: URIs
Tested with Gallary and Downloads.
Bug 3510624
Backport of Ibfa4b383463f157e18fd634e55f5be4b9adf6aa5
Change-Id: Id2815738673f3822a97e92414b84f6a5d46eb96f