Revert "Base: Prevent lock/unlock sound during music playback"

This reverts commit 22a06adcede778a388ed1371fe56f9c30ea01eb9.
Prevent SystemUI crash by limiting the number of popups on long click

Recent apps screen shows multiple popup windows by long click
for multiple items. Sometimes outdated popup windows left causes
SystemUI crash. By only having single popup window, SystemUI crash
can be avoided.

Bug: http://code.google.com/p/android/issues/detail?id=66376
Change-Id: Ifc2fbe797a2350ee9ce01092caf6087fab08d0ae
Null pointer exception in FileRotator.java

Sometimes a null pointer exception is thrown when examining files
managed by the file rotator.

The logs from the test show that the Wifi state is changed a large
number of times. On every state change, a write operation is
initiated on the file system. This will eventually result in out
of memory and the call to mBasePath.list() in the maybeRotate(...)
method in FileRotator.java will return null so the iteration will
throw a NullPointerException.

Change-Id: I5d5980d9593bc9ec75281169ca27ee591809903f