Revert "Combining the Thumbnail bitmap with the background to fix background spilling in the front."

This reverts commit 5a9dce518edb2487b76485723401751ac0be0a74.

Reason for revert: The solution is inefficient. There is already a solution in ag/17060224

Change-Id: I5b5862f1ae426c78062c5a0f481abfb13b3060cc
1 file changed