Use matrix to scale icon for splash starting window

Originally the cost would increase in proportion to the size.
Now the draw time becomes almost irrelevant to size. And the
visual appearance is almost the same as previous approach.

The icon draw time:
 News  : 32ms -> 10ms
 Clock : 46ms -> 23ms
 Dialer: 30ms -> 14ms

Bug: 187104264
Test: OpenAppMicrobenchmark
Change-Id: I9edeb367c671315374f8579bf3b91dc778bad302