Fixed thumbnail flashing bug in the inspector.

Before we loaded a drawable mime type then replace with a bitmap
thumbnail if the thumbnail wasn't null.

Now we load the thumbnail and if it failed set the image to the files
mime type.

Bug: 63528325
Test: N/A

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Change-Id: I2b7f23e7e2495cc15fbc659c1022e635f74ee89d
3 files changed