Add back button for dialpad in incallui.

Back icon resource:
https://icons.googleplex.com/#icon=ic_arrow_back

Bug: 27231038
Change-Id: Ia98f640b31322a4eda56998b5624637ea1699ed8
7 files changed
tree: 7c3b5e22ac0069910999f02e4075ae957ea376e8
  1. res/
  2. src/
  3. Android.mk
  4. AndroidManifest.xml
  5. build.gradle