Refactor ZLib and Verbatim encoders.

remoting/base/compressor_zlib.h

Index: remoting/base/compressor_zlib.h
diff --git a/remoting/base/compressor_zlib.h b/remoting/base/compressor_zlib.h
index d2cc82b93dba09909bc250c905d4eb2086dbdb74..3371d229d73806b381fcb5dd195ea32f9d3f1ce3 100644
--- a/remoting/base/compressor_zlib.h
+++ b/remoting/base/compressor_zlib.h
@@ -23,6 +23,8 @@ class CompressorZlib : public Compressor {
                        uint8* output_data, int output_size,
                        CompressorFlush flush, int* consumed, int* written);
 
+  virtual void Reset();
+
  private:
   scoped_ptr<z_stream> stream_;
 };