Don't allow MemoryFiles of negative length.

Prevents us from converting a (signed) jint into an
(unsigned) size_t and having horrible things happen.

Change-Id: I0f04e2eb9852ae7fc49b435fd0974f56e86751a4
Signed-off-by: houst0nn <houstonn@gmail.com>
Avoid SystemUI crash due to NPE

BaseStatusBar.createNotificationViews() returns null
when it reports handleNotificationError(), leading to
a forced crash of the misbehaving app. However, it
should not add a null object of Notification.Entry
since it will also crash SystemUI (crashing at compare).

Change-Id: I86678c8024e931420b0fbab1f36b330e7e75d581
Signed-off-by: houst0nn <houstonn@gmail.com>