[SysApps] Add getAVCodecs() interface to the IDL file

Add getAVCodec()s interface to the IDL file to generate
the header and code for this interface.
[SysApps] Add an data provider abstraction for the getAVCodecs()

This patch adds the basic interface needed for starting the development
of the Device Capabilities API getAVCodecs(). In the following patch we
will be adding a platform dependent implementation for querying the
list of supported codecs.
[SysApps] Implement Device Capabilities getAVCodecs() for Linux, Mac and Windows

The data provider will access the list of registered codecs from FFmpeg
and check each codec in the list is supported by Chromium or not by
converting an FFmpeg audio codec ID into its corresponding supported
codec ID in the Chromium.
[SysApps] Add stubs for Android

Linux implementation doesn't work on Android since the Android
port doesn't use FFmpeg. For now, the Android implementation
should print "not implemented" warnings.
[SysApps] Hook the AVCodecProvider into SysAppsManager

The platform specific implementation of AVCodecsProvider[Android|FFmpeg]
has been inherited from the AVCodecsProvider. So, this will allow us to
initialize the platform specific instance of the provider.
[SysApps] Add browsertests for DeviceCapabilities getAVCodecs()
[SysApps] Add AVCodecsProvider unit tests
[SysApps] Add unit test for the GetAVCodecsProvider()
Roll chromium-crosswalk to 0112237.

0112237 [SysApps] Expose ffmpeg function signatures needed by Device Capabilities API
Merge pull request #1447 from nagineni/devcap_avcodecs

[SysApps] Implement the Device Capabilities getAVCodecs() API