Increase the buffer size in AudioRendererImpl to fix muted playback rate

This CL temporarily removes GetBufferSizeForSampleRate() and uses
SelectSamplesPerPacket() to determine the size of samples_per_packet in
AudioDevice. This restores the buffer size that AudioRendererImpl
used prior to r113821. SelectSamplesPerPacket() calculates a much larger
samples_per_packet value than GetBufferSizeForSampleRate(), so it fixes
the issue described in 108239.

This CL also does some mild refactoring to move audio_common.cc into
audio_util.cc.

BUG=108239
TEST=media_unittests,content_unittests, manual testing of different playback rates

Review URL: https://chromiumcodereview.appspot.com/9416085

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@123292 0039d316-1c4b-4281-b951-d872f2087c98
8 files changed