Improve ANR diagnostics.

Print more details about the exact reason that an ANR has occurred.
Also start checking that the window actually has a registered
input connection that is not in a broken state.  These windows
are supposed to be cleaned up by the window manager promptly
as if the app had crashed but the pattern of ANRs we are observing
suggests that broken windows might be sticking around longer than
they should.

Bug: 17721767
Change-Id: Ie2803a3fa9642381ecadc198fec15e1b70d93c20