Adding video reader/writer APIs.

Right now only IVF format is supported which is enough for example code.
Other formats like y4m, webm, raw yuv will be supported later.

Change-Id: I34c6f20731c1851947587ca5c589d7856b675164
diff --git a/examples.mk b/examples.mk
index b2bdf68..078ce34 100644
--- a/examples.mk
+++ b/examples.mk
@@ -77,20 +77,29 @@
 simple_decoder.GUID                 = D3BBF1E9-2427-450D-BBFF-B2843C1D44CC
 simple_decoder.SRCS                += ivfdec.h ivfdec.c
 simple_decoder.SRCS                += tools_common.h tools_common.c
+simple_decoder.SRCS                += video_common.h
+simple_decoder.SRCS                += video_reader.h video_reader.c
 simple_decoder.DESCRIPTION          = Simplified decoder loop
 EXAMPLES-$(CONFIG_VP8_DECODER)     += postproc.c
 postproc.SRCS                      += ivfdec.h ivfdec.c
 postproc.SRCS                      += tools_common.h tools_common.c
+postproc.SRCS                      += video_common.h
+postproc.SRCS                      += video_reader.h video_reader.c
 postproc.GUID                       = 65E33355-F35E-4088-884D-3FD4905881D7
 postproc.DESCRIPTION                = Decoder postprocessor control
 EXAMPLES-$(CONFIG_VP8_DECODER)     += decode_to_md5.c
 decode_to_md5.SRCS                 += md5_utils.h md5_utils.c
 decode_to_md5.SRCS                 += ivfdec.h ivfdec.c
 decode_to_md5.SRCS                 += tools_common.h tools_common.c
+decode_to_md5.SRCS                 += video_common.h
+decode_to_md5.SRCS                 += video_reader.h video_reader.c
 decode_to_md5.GUID                  = 59120B9B-2735-4BFE-B022-146CA340FE42
 decode_to_md5.DESCRIPTION           = Frame by frame MD5 checksum
-
 EXAMPLES-$(CONFIG_VP8_ENCODER)  += simple_encoder.c
+simple_encoder.SRCS             += ivfenc.h ivfenc.c
+simple_encoder.SRCS             += tools_common.h tools_common.c
+simple_encoder.SRCS             += video_common.h
+simple_encoder.SRCS             += video_writer.h video_writer.c
 simple_encoder.GUID              = 4607D299-8A71-4D2C-9B1D-071899B6FBFD
 simple_encoder.DESCRIPTION       = Simplified encoder loop
 EXAMPLES-$(CONFIG_VP8_ENCODER)  += twopass_encoder.c
@@ -103,6 +112,8 @@
 EXAMPLES-$(CONFIG_VP8_ENCODER)  += decode_with_drops.c
 decode_with_drops.SRCS          += ivfdec.h ivfdec.c
 decode_with_drops.SRCS          += tools_common.h tools_common.c
+decode_with_drops.SRCS          += video_common.h
+decode_with_drops.SRCS          += video_reader.h video_reader.c
 endif
 decode_with_drops.GUID           = CE5C53C4-8DDA-438A-86ED-0DDD3CDB8D26
 decode_with_drops.DESCRIPTION    = Drops frames while decoding