Use intptr_t to represent window IDs on all platforms.

Previously void* was used on windows which makes it harder to work
with the IDs in cross-platform code.

R=alexeypa@chromium.org

Review URL: https://webrtc-codereview.appspot.com/1672004

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@4237 4adac7df-926f-26a2-2b94-8c16560cd09d
2 files changed