Updating the header bar item visibility with the task view frame.

- In freeform mode, we hide the buttons depending on the available width
  of the task view
- Also fixes the rounded corners on the task views as the frame changes
- Tweaking the freeform workspace background

Change-Id: Iec9352acb5cb3ce95c09ff6d1026a9900717d3e6
7 files changed