Fix visibility of multiple non-fullscreen activities.

Issue detail:
Assume X, Y are non-fullscreen activities.
 a.Home starts an activity X in task A in application stack.
 b.X starts an activity Y in <task A> or <new task B>
 c.Activity X will be invisible.

How to fix:
Because the function "isActivityOverHome" means an activity is able to see home.
But there may have many non-fullscreen activities between the top non-fullscreen activity and home.
If flag "behindFullscreen" is set, those middle activities will be invisible.
So it should only take care from who is adjacent to home.
Then check two flags frontOfTask(task root) and mOnTopOfHome for constraining the condition.

Change-Id: I60bcea304976414e44835a0a38675aae365e9e19
Before requerying a cursor, check if it is closed.

Before updating a cursor,
it needs to be checked if it is valid.
Currently a defence code only checks
if it is not null.
But in case of "Cursor", it is not valid,
if it is closed.
So just like in CursorAdapter.onContentChanged(),
add the additional defence code to check validation.

Change-Id: I1302f1b6d009897815d4bdb2f20f625688cf9901
Add NULL check in updateProxyConfig

If the exclusionList was null in updateProxyConfig the VM would
crash when converting it to a UTF8 string. Avoid this by adding a
null check.

Change-Id: I0d8106fd54385bd9ae9c652a6c67d459a119cf2b
MountService listeners can not be unregistered

When unregistering MountService listeners, their Binder proxy
objects were compared to registered listeners instead of their
backing objects.

Change-Id: Ie98a686b1d17544f1eda59fb3eb0dc02d836c1b2
Fix preference puts with "null" values.

Null values were being written out as <null /> elements in the
XML prefs file (as expected). This allowed the getFoo() functions
to work correctly because they treated null values as missing mappings
but containsKey would fail.

bug: https://code.google.com/p/android/issues/detail?id=64563
Change-Id: I1f466d01db96bf26e208d4fed3a6f257228bea5d
Fix a JNI local reference leak in MediaDrm

A reference leak was found in the subtitle usecase that also
applies to android_media_MediaDrm.cpp
(Code taken from the similar fix in android_media_MediaPlayer.cpp)

Change-Id: Icc4b25e4adc9a600ff4ac99a7a8478bb55a6e348
Fixed race condition in Spinner.DialogPopup on null reference.

NullPointerException is triggered when DialogPopup is
dismissed due to object mPopup being null when not showing.
Race condition is triggered when dialog is dismissed before
touch event to dismiss dialog has been processed properly.

Fixed by adding a null check prior to accessing mPopup object.

Change-Id: I3c4fe9c279d92a7103fb4f68189d1d42beedc606