LayoutLib: Fix issue with rendering mode.

When the layout content is embedded inside a decor layout
to emulate system bar (top or bottom) and title bar (or action bar)
then the code computing the full required size based on the RenderingMode
would fail because the decor layout would prevents the content layout to
take as much room as possible.
There is also an issue with the way we know render dialogs as the
dialogs usually as a frame with some padding and the previous measurements
would not take into account the dialog padding when increasing the
screen size.

This fix makes the code measure the size of the content layout in the
normal rendering, and then separately from the root layout with the proper
MeasureSpec to let the content grown. The difference in size is then added
to the screen size.

Bug: http://code.google.com/p/android/issues/detail?id=15892

Change-Id: Ibb9ca2a67c6c450d10d9f9a8050536e094650f8b
1 file changed