Added a virtual function to handle PSNR packets.

Change-Id: Id2a6372c691a14f19bbeed217a93a9df03e81e75

Modified EncoderTest class to have separate member variables
for initialization time and per-frame.

Change-Id: I08a1901f8f3ec16e45f96297e08e7f6df0f4aa0b

The stats buffer needs to be reset between runs of the
encoder. I added a Reset() function to TwopassStatsStore
and called it at the beginning of each encode.

This enables us to run multiple encodes which was
previously not possible since there was no way to reset
the stats between runs.

Change-Id: Iebb18dab83ba9331f009f764cc858609738a27f9

This commit adds the ability of validating matched encoder and
decoder to unit tests.

Change-Id: Ie00d69a42477b6a69b324a6bd134939684f7300b

Change-Id: I813fa94c83df6282f382b24bbaccb1fe2fa94276

The lower complexity modes may not generate a keyframe automatically.
This behavior was found when running under Valgrind, as the slow
performance caused the speed selection to pick lower complexities than
when running natively. Instead, use a fixed complexity for the
realtime auto keyframe test.

Affected tests:
  AllModes/KeyframeTest.TestAutoKeyframe/0

Change-Id: I44e3f44e125ad587c293ab5ece29511d7023be9b

To do so we add a framework for encoding a yv12 file..

Change-Id: I94a061eb916beaf6cde920cf1aaadb6eed10a717

Implements a couple simple tests of the encoder API using the gtest
framework:

  TestDisableKeyframes
  TestForceKeyframe
  TestKeyframeMaxDistance

Change-Id: I38e93fe242fbeb30bb11b23ac12de8ddc291a28d