Fixes for optical bounds feature.

1. Make the feature opt-in (ViewGroup::layoutMode defaults to CLIP_BOUNDS) without inheritance.
2. Rename COMPONENT_BOUNDS to CLIP_BOUNDS.
3. Rename LAYOUT_BOUNDS to OPTICAL_BOUNDS.
4. Complete GridLayout implementation.
5. Change the default_gap between components to 8dp, to align with the Style Guide.

Change-Id: I8d40dfc5f4ca469f6424eb3ff60d07bec56e3a9f
13 files changed