[Cast] Track audio queued in encoder; account for it in ShouldDropNextFrame().

media/cast/sender/audio_encoder_unittest.cc

Index: media/cast/sender/audio_encoder_unittest.cc
diff --git a/media/cast/sender/audio_encoder_unittest.cc b/media/cast/sender/audio_encoder_unittest.cc
index 0764148a4cfa41da81454a7b1f1b19925055f60e..a33ed3bc0ed00aa6393715f37d98923a2edb8dc3 100644
--- a/media/cast/sender/audio_encoder_unittest.cc
+++ b/media/cast/sender/audio_encoder_unittest.cc
@@ -39,7 +39,8 @@ class TestEncodedAudioFrameReceiver {
     upper_bound_ = upper_bound;
   }
 
-  void FrameEncoded(scoped_ptr<EncodedFrame> encoded_frame) {
+  void FrameEncoded(scoped_ptr<EncodedFrame> encoded_frame,
+                    int samples_skipped) {
     EXPECT_EQ(encoded_frame->dependency, EncodedFrame::KEY);
     EXPECT_EQ(static_cast<uint8>(frames_received_ & 0xff),
               encoded_frame->frame_id);