Fix Windows x64 errors in video_codecs_test_framework

Fixed a few size_t converted to int warnings (interpreted as errors).
Fixed cpplint warnings.

BUG=webrtc:1323
TEST=manual compile on Windows with GYP_DEFINES=target_arch=x64 and
ninja -C out\Debug_x64 (also compiled with Release_x64)

Review URL: https://webrtc-codereview.appspot.com/1097011

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@3507 4adac7df-926f-26a2-2b94-8c16560cd09d
5 files changed