App Helper test base fixes.

1. Use the open and exit wrappers in the App Helper tests.
2. Hold the natural orientation regardless of current.

* Fixes the GoogleKeyboardHelperTest
* Note: orientation bug occurred because this is called on the launcher, which is
always in the "natural orientation."

Test: GoogleKeyboardHelperTest
Test: AppHelperTests
Change-Id: I89b06498116f9c88e7e84f94a132b24762c25803