Use posix_memalign for OS_NACL instead of memalign, remove TODO for docs.

We finally added it to the nacl newlib headers. Besides the
headers there used to be a bug in the posix_memalign
implementation which prevented it from being useful. That's also fixed.

BUG=138579

Review URL: https://codereview.chromium.org/89703005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237695 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237695
Support use_alsa==0 on Linux

This moves the ALSA audio code from media/audio/linux to
media/audio/alsa and splits Linux's CreateAudioManager() into a new
file. This function chooses which AudioManager subclass to use on Linux.

When use_alsa==0 on Linux, the fallback audio manager is changed from
ALSA to a new fake implementation that always has an empty set of devices
and will only return fake streams.

This allows us to compile with no audio support on Linux. In particular,
we can compile for targets that don't have the ALSA libraries available.
Obviously, it's not (yet) possible to play audio in this configuration.

BUG=318315, 318413

Review URL: https://codereview.chromium.org/89793003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237696 0039d316-1c4b-4281-b951-d872f2087c98
Allow drawing IOSurfaces from any IOSurfaceContext

Create a separate offscreen context, shared by all contexts, to be used
for asynchronous readback operations.

Move some functions (vsync check and vendor check) from the IOSurface
to the IOSurfaceContext where they belong.

BUG=318751

Review URL: https://codereview.chromium.org/90003003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237697 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237696
SVN changes up to revision 237697
Take into account manifest permissions when upgrading an extension.

* IsPrivilege increase needs to check for ManifestPermission changes too.
* Add unit tests.

BUG=

Review URL: https://codereview.chromium.org/90023002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237698 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237698