Refactoring in ContactDrawable to pick a color.

Strategy pattern to pick a color in the letter tile.

Thanks to this, subimplementations can draw the letter tiles
for avatars differently, and still use the all the features
of the ContactDrawable.

Bug: 16378212 Draw letter tile for non-Gmail avatars
Change-Id: I999aa43724ba0e4dd23f2106133aaa34ee3ba008
3 files changed