Initialize pointer members to NULL to avoid illegal reference

mBitmap and mTexture is not initialized to NULL which causes
illegal address access when it fails to be created from
oversized bitmap.
Cherry-picked from AOSP: https://android-review.googlesource.com/#/c/79320/

Change-Id: Iea54bec8788bc5f3a10040fdb43f416c0d41a14c
MediaFocusControl: Deny audio focus if notification stream is 0

Previously audio focus would be granted regardless of notification
volume, meaning that if notifications are muted the media stream would
still be dimished for focus. By checking if STREAM_NOTIFICATION is 0 and
if a notification stream is requesting focus, this is no longer an issue.

Change-Id: Ie10a64e58ce77174a3bbdeaa936646d40c24404f
Signed-off-by: Evan Anderson <evan1124@gmail.com>
Set Settings.Global.WIFI_SCAN_ALWAYS_AVAILABLE default value

To be able to customize the "WiFi scan always available"
setting we need to set a default value.

Change-Id: I3673f2613ab9b6a947aed7e29d4cc876140c2180
Fix error checking in MemoryFile.

mmap returns MAP_FAILED on failures, not 0 (NULL).
Also, convert some C style casts to C++ since they
make intent clearer.

Change-Id: I367993c73e9ee576f11ebe76e530d2c2f27c662d
Fixed stylus eraser being rejected by palm rejection

The stylus eraser appeared not to work, i.e. Android did not respond to
input from the eraser. It turned out that all input except stylus input
is rejected when palm rejection is activated. The problem was that the
eraser itself activates palm rejection when it hovers. The solution is
to allow the eraser during palm rejection. This solution makes sense
because the eraser input works in the exact same way as normal stylus
input.

Change-Id: I90824500be7613af4f00427c59ce828528b632f7